BELIEVE IN ALGEBRA, NOT CALCULATOR

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blackpenredpen | 曹老師

Пікірлер: 1 700

  • @aasyjepale5210
    @aasyjepale52105 жыл бұрын

    i did some mental math, but hit a wall at trying to find the square root of 63,252,753,001

  • @iamgroot3615

    @iamgroot3615

    5 жыл бұрын

    that’s some impressive mental math assuming you’re telling the truth . Is there a trick or something

  • @AngryAxew

    @AngryAxew

    5 жыл бұрын

    @@iamgroot3615 theres no trick hes probably lying

  • @AngryAxew

    @AngryAxew

    5 жыл бұрын

    r/iamverysmart

  • @marvinfung2050

    @marvinfung2050

    5 жыл бұрын

    AngryAxew there's no reason not to be able to mental math those numbers Like 500(500+1) which is easier which is 250000+500 and it similar to the end

  • @narayanankannan6787

    @narayanankannan6787

    5 жыл бұрын

    I mean it's OBVIOUSLY 251501.

  • @Armbrust666
    @Armbrust6665 жыл бұрын

    Wow... this essentially proved that if you take the product of four consecutive -numbers- integers and add one to it, than it's gone be a square number.

  • @ClimateAdam

    @ClimateAdam

    5 жыл бұрын

    Awesome! Good spot!

  • @fanyfan7466

    @fanyfan7466

    5 жыл бұрын

    Gábor Tóth holy shit you’re right! That’s crazy man

  • @blackpenredpen

    @blackpenredpen

    5 жыл бұрын

    Yup!!

  • @kingbeauregard

    @kingbeauregard

    5 жыл бұрын

    The most pathological case I can think of is -1 thru 2, and yes indeed I get 1, which is a perfect square.

  • @pcklop

    @pcklop

    5 жыл бұрын

    My professor had us prove a more general result: take the product of four numbers in arithmetic sequence, then add the fourth power of their common difference. Show that the result is a perfect square.

  • @threadeater345
    @threadeater3455 жыл бұрын

    1990: we'll have flying cars by 2019 2019: 2=1+1, wow I'm a genius

  • @blackpenredpen

    @blackpenredpen

    5 жыл бұрын

    LOL

  • @ghotifish1838

    @ghotifish1838

    3 жыл бұрын

    2+2 is 4, minus one that's three quick maths

  • @Kyanzes

    @Kyanzes

    3 жыл бұрын

    Flying cars... you can't even have a sharpie that could change color. Say, red and black.

  • @santinodemaria2818

    @santinodemaria2818

    3 жыл бұрын

    @@ghotifish1838 topical meme reference

  • @unutentediyoutube3282

    @unutentediyoutube3282

    3 жыл бұрын

    Well it can also be 2=500-498

  • @yuliaokhremenko6613
    @yuliaokhremenko66135 жыл бұрын

    I just started learning English, but the explanations are clear and interesting even at my levels of English. Thanks a lot 😁👍

  • @blackpenredpen

    @blackpenredpen

    5 жыл бұрын

    Юлия Охременко I am Glad to hear!

  • @enhace15anos.83

    @enhace15anos.83

    4 жыл бұрын

    x2

  • @corona8073

    @corona8073

    4 жыл бұрын

    U r indian Chinese korean or ....???

  • @donovanholm

    @donovanholm

    4 жыл бұрын

    @@harelavv8806 the name may seem obviously Russian to some but not all

  • @siddharthsoni2101

    @siddharthsoni2101

    3 жыл бұрын

    @@blackpenredpen hii

  • @sethdon1100
    @sethdon11005 жыл бұрын

    Olympic math taught me that insanely hard problems often had elegant solutions, this is no exception.

  • @blackpenredpen

    @blackpenredpen

    5 жыл бұрын

    : ))))

  • @hafizh8461

    @hafizh8461

    4 жыл бұрын

    @@leif1075???

  • @hemandy94

    @hemandy94

    4 жыл бұрын

    @@leif1075 people like these are called problem solvers...

  • @drudi1

    @drudi1

    4 жыл бұрын

    @@leif1075 well it took me about 5min to solve it so I think is not impossible to solve. All of this types of equations where you have 4 consecutive numbers multipled are done like this

  • @jayasri6764

    @jayasri6764

    4 жыл бұрын

    Lol,This problem is actually super easy,(Every single Olympiad contestant would have solved this question,at some point of their life) .Insanely hard problems need not have simple solutions . That's a downside of the math Olympiad .They make you expect difficult problems have simple solutions.(Although,most imo contestants don t fall for this fallacy).Real insanely hard problems have not been solved by anyone,yet.

  • @Hypoli
    @Hypoli3 жыл бұрын

    My last words whispered in a final breath : "Don't forget the +1"

  • @not_So_Random-Dude

    @not_So_Random-Dude

    3 жыл бұрын

    😂

  • @68plus1.

    @68plus1.

    2 жыл бұрын

    LMFAOOO

  • @naiknaik8812

    @naiknaik8812

    2 жыл бұрын

    He never resumed the video

  • @user-tk4dj4il5s

    @user-tk4dj4il5s

    10 күн бұрын

    He added the one wdym 🧐

  • @BryanLu0
    @BryanLu05 жыл бұрын

    Instead distributing at 4:18 u = x^2 + 3x + 1 (u - 1)(u + 1) + 1 = u^2 So the root is x^2 + 3x + 1 = 251501

  • @blackpenredpen

    @blackpenredpen

    5 жыл бұрын

    Bryan Lu omg that cat!!!!

  • @AmitBentabou

    @AmitBentabou

    5 жыл бұрын

    Or even u=x^2+3x, then u^2+2u+1

  • @matias12381

    @matias12381

    5 жыл бұрын

    digno de nyan cat, jajajajaj

  • @mattat3847

    @mattat3847

    5 жыл бұрын

    My life is a lie. I thought u subbing was only for integrals

  • @RunstarHomer

    @RunstarHomer

    5 жыл бұрын

    @@mattat3847 nah man, sub whenever it makes the problem simpler

  • @leagueplays2100
    @leagueplays21005 жыл бұрын

    i put it in my calculator and got 251501, that was easy

  • @bowtangey6830

    @bowtangey6830

    4 жыл бұрын

    Boo!

  • @Netherexio

    @Netherexio

    3 жыл бұрын

    @The Balton American calculators are beasts

  • @paradox9265

    @paradox9265

    3 жыл бұрын

    @@Netherexio Agreed but Americans aren’t

  • @Netherexio

    @Netherexio

    3 жыл бұрын

    @@paradox9265 What do you mean?

  • @user-yp6eb5wj4w

    @user-yp6eb5wj4w

    3 жыл бұрын

    It was easy, but not so beautiful like this)

  • @blackpenredpen
    @blackpenredpen5 жыл бұрын

    Did you know that 2 = 1 + 1?? I bet not! jk : )

  • @williamadams137

    @williamadams137

    5 жыл бұрын

    blackpenredpen No i don’t, i need a calculator to this

  • @snejpu2508

    @snejpu2508

    5 жыл бұрын

    That's pretty funnt, but sometimes such things are the most difficult to see, for example: we have f(x)=x^4+8x^3+18x^2+8x+17, and a question, for which x, the function f(x) is a prime. You can check infinitely many cases and never know the answer, but what makes this question easy (but on the other hand is not so obvious), is that 18=17+1. Because then we have (x^2+1)(x^2+8x+17), which has to be a prime. One of them has to be = 1, the other one has to be some prime then... We are left with only 2 cases, because we know, that 18=17+1. : )

  • @theolbiterator5408

    @theolbiterator5408

    5 жыл бұрын

    No but I knew 2= 0.9+1.1.

  • @chaitanyagadekar5025

    @chaitanyagadekar5025

    5 жыл бұрын

    I Known 2+2 = 5

  • @clubstepdj

    @clubstepdj

    5 жыл бұрын

    What i know is 5/2 = 2 with int data type

  • @ganaraminukshuk0
    @ganaraminukshuk05 жыл бұрын

    "If you're using a calculator, why are you watching this video?" Sanity check.

  • @blackpenredpen

    @blackpenredpen

    5 жыл бұрын

    hahahahaa

  • @andrel8243

    @andrel8243

    3 жыл бұрын

    I am a calculator, not a person

  • @mysticdragonex815

    @mysticdragonex815

    2 жыл бұрын

    *laughs in Shakuntala Devi

  • @TheS1lentX
    @TheS1lentX5 жыл бұрын

    Jeez thats smart *proceeds to use the calculator to prove that 251501 is the right answer*

  • @mr.n1933
    @mr.n19335 жыл бұрын

    Dafuq did i jusf watch.i lost it when the 2=1+1

  • @executorarktanis2323

    @executorarktanis2323

    4 жыл бұрын

    You are not nerdy enough

  • @maheshagrawal7779
    @maheshagrawal77795 жыл бұрын

    no 2=1+1/2+1/4+1/8+1/16... you have got many misconceptions blackpenredpen!!!

  • @iabervon

    @iabervon

    5 жыл бұрын

    When he writes 1, he's obviously just abbreviating 1/2+1/4+1/8+1/16+...

  • @InDstructR

    @InDstructR

    5 жыл бұрын

    @@iabervon and when he writes 1/2 he's abbreviating for 1/4+1/8+1/16+...

  • @agces2001

    @agces2001

    5 жыл бұрын

    @@InDstructR And when he writes 1/4 he's abbreviating 1/8 + 1/16 + 1/32+...

  • @InDstructR

    @InDstructR

    5 жыл бұрын

    @ki kus won't stop me, And when he writes 1/8 he's abbreviating 1/16+1/32+1/64+1/128+...

  • @shounakghosh8595

    @shounakghosh8595

    5 жыл бұрын

    Whoa that converged quickly

  • @Inujasa88
    @Inujasa885 жыл бұрын

    0:10 is this a pewdiepie reference? 😂😂

  • @albel2094

    @albel2094

    5 жыл бұрын

    He liked it!!!

  • @randomdude9135

    @randomdude9135

    4 жыл бұрын

    @@albel2094 yupp

  • @randomdude9135

    @randomdude9135

    4 жыл бұрын

    Yupp

  • @tanmay8017
    @tanmay80172 жыл бұрын

    I remember solving this exact question in my JEE ( Mains ) exam.

  • @classicmelodyvetrivel710

    @classicmelodyvetrivel710

    2 жыл бұрын

    @Sanat R mains usually has easy questions

  • @Avighna

    @Avighna

    Жыл бұрын

    @Sanat R - Study Vlogs Sure, yeah, "easy question" 😬

  • @Avighna

    @Avighna

    Жыл бұрын

    @Sanat R - Study Vlogs Woah, really? What kinda questions do they ask? Could you send me a link?

  • @blackflash9935
    @blackflash99355 жыл бұрын

    5:48 “Back in my day kids would use *ALGEBRA* but now their brains are rotting from these darn *CALCULATORS* ”

  • @steve2817
    @steve28175 жыл бұрын

    1 + 1 = 3 And sinx/n=six=6.

  • @rio_agustian_

    @rio_agustian_

    5 жыл бұрын

    You stupid, 1 + 1 ≠ 3 3 = 2 + 1 π = 2 + 1 π - 1 = 2

  • @CookieJar2025

    @CookieJar2025

    5 жыл бұрын

    @@rio_agustian_ so π = 3 lol nice discovery

  • @Kevin-14

    @Kevin-14

    5 жыл бұрын

    @@CookieJar2025 e = 3 = π

  • @SameerKhan-nd5qb

    @SameerKhan-nd5qb

    5 жыл бұрын

    @@rio_agustian_ noob

  • @SameerKhan-nd5qb

    @SameerKhan-nd5qb

    5 жыл бұрын

    @@Kevin-14 lool nooob

  • @rd8396
    @rd83965 жыл бұрын

    Take x ^2 + 3x = a Then in step 2 a(a+2) + 1 a^2 + 2a + 1 = (a+1)^2

  • @mat1305h

    @mat1305h

    5 жыл бұрын

    Yes much easier, and you see it imediatly too.

  • @Polarspy

    @Polarspy

    5 жыл бұрын

    was about to say this, i think it's a lot more intuitive

  • @milanmitreski7657

    @milanmitreski7657

    5 жыл бұрын

    Isn't it beautiful how one problem can be solved in diffrent ways, even if the idea and the method are nearly the same. That's why we love maths.

  • @sanjaisrao484

    @sanjaisrao484

    5 жыл бұрын

    @@milanmitreski7657 Yes

  • @akshetpatial5466

    @akshetpatial5466

    5 жыл бұрын

    You extra smart boy the time required here will be same

  • @pfever
    @pfever5 жыл бұрын

    Sorry...Time over! give me your exam!

  • @DatSwif
    @DatSwif3 жыл бұрын

    This is beautiful. I've been looking at it for five hours now

  • @jekoddragon6227
    @jekoddragon62275 жыл бұрын

    now do it with CALCULUS

  • @davidappell3105

    @davidappell3105

    3 жыл бұрын

    Why do you think this is funny?

  • @gabrielpinhal8325

    @gabrielpinhal8325

    3 жыл бұрын

    @@davidappell3105 because suffering is funny

  • @sanchit6107

    @sanchit6107

    2 жыл бұрын

    @@davidappell3105 Its FUNI

  • @chaitanyagadekar5025
    @chaitanyagadekar50255 жыл бұрын

    0:09 That was PowerFul

  • @tiborgrun6963
    @tiborgrun69635 жыл бұрын

    Not only 2 = 1+1, but also 0 = 1-1. From the second row: (x^2+3x+1-1)(x^2+3x+1+1)+1 and per the third binomial equation = (x^2+3x+1)^2 -1^2 +1 = (x^2+3x+1)^2

  • @etemkaandelibas3649

    @etemkaandelibas3649

    5 жыл бұрын

    I didn't understand. Where did you use binomial expansion

  • @jinja3113

    @jinja3113

    5 жыл бұрын

    0 = 1-1 1 = 1*1 2= 1+1

  • @yogeshpathak73

    @yogeshpathak73

    4 жыл бұрын

    I didn't see any binomial here... But what i see is that you used the form (a+1)(a-1) + 1 = a^2 - 1 +1= a^2

  • @Bayerwaldler

    @Bayerwaldler

    4 жыл бұрын

    @@yogeshpathak73 I think Tibor Grün is from Germany. In German school curriculum the formula (a+b)*(a-b) = a^2 - b^2 is known as 3. binomial formula. b=1 is a special case.

  • @yogeshpathak73

    @yogeshpathak73

    4 жыл бұрын

    Oh ok... Didn't know that. Thanks.

  • @dr3w199
    @dr3w1995 жыл бұрын

    Nice. I did it this way: Assume that the expression is a square number so: x(x+1)(x+2)(x+3)+1 = n^2 x(x+1)(x+2)(x+3) = n^2 - 1 x(x+1)(x+2)(x+3) = (n+1)(n-1) What I did then is realise that the factors of the product on the right differ by 2. Playing around you can find that: x(x+3) = x^2+3x = n-1 (x+1)(x+2)=x^2+3x+2 = n+1 So n = x^2 + 3x + 1 Not as neat as your method though! Thanks for the video

  • @juanbomfim22

    @juanbomfim22

    5 жыл бұрын

    OMG ive almost done it completely. i just stopped at (n+1)(n-1) lol WD! i mean 'not that almost' lmao

  • @joshuamason2227

    @joshuamason2227

    5 жыл бұрын

    How do I play around with it

  • @dr3w199

    @dr3w199

    5 жыл бұрын

    @@joshuamason2227 Well you have the product of 3 binomials and a monomial for which we can multiply in any order. If you try a few cases, or think about it you spot that x(x+3) and (x+1)(x+2) have a difference of 2.

  • @joshuamason2227

    @joshuamason2227

    5 жыл бұрын

    @@dr3w199 okie

  • @sunnykarwani3556

    @sunnykarwani3556

    3 жыл бұрын

    Damn... It's a great method. Neat work. 💯

  • @agabe_8989
    @agabe_89894 жыл бұрын

    0:01 that's my life philosophy now

  • @lucasxue2211
    @lucasxue22112 жыл бұрын

    i remember my math teacher asking me to prove that n(n+1)(n+2)(n+3) + 1 is always a perfect square given that n is an integer

  • @asa-ze1kn
    @asa-ze1kn5 жыл бұрын

    I'm only in 8th grade Algebra 1 but I was using variables to find how some of your factorizations works. You went from (x^2+3x)(x^2+3x+2)+1 to (x^2+3x)(x^2+3x+1)+(x^2+3x+1). What I did was set (x^2+3x) to a variable (a). (a)(a+2)+1 a^2+2a+1 (a+1)(a+1) Now substitute back in. (x^2+3x+1)(x^2+3x+1) When in doubt use variables..

  • @trueriver1950

    @trueriver1950

    4 жыл бұрын

    Yes, that's using even more algebra than BPRP did.

  • @zocker2586

    @zocker2586

    4 жыл бұрын

    Well yes because using the variables is actually the logic behind the solution, it's just that it was invisible throughout the process :D

  • @baranibarani4970

    @baranibarani4970

    4 жыл бұрын

    Where r u from?

  • @sanjanabiswas9774

    @sanjanabiswas9774

    3 жыл бұрын

    Agreed! Variables always help to proceed the solution.

  • @enricomassignani

    @enricomassignani

    3 жыл бұрын

    I put x=500 but multiplied everything. In the end i got to sqrt((x+y)^2) with x=500 and y=501^2

  • @isaacdeutsch2538
    @isaacdeutsch25384 жыл бұрын

    I chose to make x = 502, which ends up yielding a nice difference of squares and a two term quadratic, which is much easier to distribute. The quartic you get has a palindromic pattern reminiscent of pure binomial coefficients, making it tempting to say the golden ratio is a root. It is, in fact, a root, so synthetically divide the quartic by the golden ratio identifying polynomial, x² - x - 1. You end up with the golden ratio identifying polynomial again, meaning that the original quartic in that square root is (x² - x - 1)², so cancel the power and the root. Plug 502 back in for x, some quick multiplying and subtracting by hand and you've got 251501.

  • @mhm6421
    @mhm6421 Жыл бұрын

    Continueing from: sqrt( (x^2 + 3x) (x^2 + 3x + 2) + 1 ) let y = x^2 + 3x sqrt( y * (y + 1) + 1 ) = sqrt( y^2 + y + 1 ) = sqrt( (y+1)^2 ) = y + 1 = x^2 + 3x + 1 = (x + 1) (x + 2) - 1 = 501 * 502 - 1 = 251501 much easier to multiply :p

  • @razvy3827

    @razvy3827

    Жыл бұрын

    that is what i wanted ti type nice 👍

  • @detachedmars158
    @detachedmars1585 жыл бұрын

    You can also put a +1-1 inside the x^2+3x bracket and it'll be in the form of (a+b)(a-b).

  • @kilindogma9711

    @kilindogma9711

    5 жыл бұрын

    that's what i thought he was gonna do as well but what he did was cool as well.

  • @ssdd9911

    @ssdd9911

    5 жыл бұрын

    why?

  • @iabervon

    @iabervon

    5 жыл бұрын

    Yeah, (x-1)(x+1)+1=x^2-1^2+1 seems easier to find than multiplying out exactly the right portion of the big expression.

  • @ericzgrey
    @ericzgrey3 жыл бұрын

    I love this. You did a great job of laying out a good challenge.

  • @TheGaberGuy
    @TheGaberGuy3 жыл бұрын

    Blew my mind! Earned yourself a new subscriber! Keep up the good work!👍

  • @LudwigvanBeethoven2
    @LudwigvanBeethoven25 жыл бұрын

    Every body knows 1+1=2 but i know 1+1 =/= 3

  • @blackpenredpen

    @blackpenredpen

    5 жыл бұрын

    ♫♪Ludwig van Beethoven♪♫ Hahahhaha

  • @jgsh8062

    @jgsh8062

    3 жыл бұрын

    I’ve got you all beat with 1+1 > 0

  • @JDguy11222

    @JDguy11222

    3 жыл бұрын

    @@jgsh8062 nah mine's better 1+1≠1+1

  • @msmmath87
    @msmmath875 жыл бұрын

    Really good solution! GOOD Teacher👍

  • @ugursoydan8187
    @ugursoydan81873 жыл бұрын

    a very good perspective and a very good solution. thank you!!!

  • @SawkTheFighter13
    @SawkTheFighter132 жыл бұрын

    Why are your videos so entertaining? I'm so glad I came across this channel.

  • @workout9594
    @workout95944 жыл бұрын

    3:20 I solved it differently. Let y= x^2+3x. Then substitute y into the expression making y(y+2)+1, distribute so y^2+2y+1 and that is a perfect square of (y+1)^2. Here, the square root and exponent cancel each other leaving y+1, sub back in x and then easily find the answer :)

  • @matthewmanzanares6798

    @matthewmanzanares6798

    Жыл бұрын

    this is also what I did and I think that this is a bit better because you don't have to split 2 into 1 + 1 and do the rest

  • @cheesecircle3033

    @cheesecircle3033

    8 ай бұрын

    That's what I did as well

  • @MrShad
    @MrShad5 жыл бұрын

    What a incredible content. Im a student of math (i'll be a teacher in the future) from Brazil. Thank you so much for sharing knowledge!

  • @-Mohammed_S
    @-Mohammed_S3 жыл бұрын

    Your explanation is awesome . I like your teaching very much. Thanks

  • @thatssokwekwe
    @thatssokwekwe Жыл бұрын

    I expressed it as sqrt((501.5-1.5)(501.5-0.5)(501.5+0.5)(501.5+1.5)+1) You get two a^2-b^2 expressions that you can multiply out, add the 1, and then factor into a squared quadratic expression Very neat and, as someone mentioned elsewhere, it generalizes to “1 plus the product of any four consecutive integers is a perfect square”

  • @ozonejgs2887
    @ozonejgs28875 жыл бұрын

    I am so impressed with myself, I actually used the same method you did before watching the video =D

  • @blackpenredpen

    @blackpenredpen

    5 жыл бұрын

    Jan Wrobel nice!!!!

  • @paawanjethva
    @paawanjethva5 жыл бұрын

    Everybody knows e^{iτ}=1 . . . . But I know 1=e^{iτ}

  • @blackpenredpen

    @blackpenredpen

    5 жыл бұрын

    Nice!!!

  • @paawanjethva

    @paawanjethva

    5 жыл бұрын

    @@user-bd9mu3ee1i That's e^{iπ}. τ=2π

  • @fgvcosmic6752

    @fgvcosmic6752

    5 жыл бұрын

    My mans using tau! Up top!

  • @peterg644

    @peterg644

    4 жыл бұрын

    @@user-bd9mu3ee1i he's using tau not pi

  • @makotoca4429
    @makotoca44295 жыл бұрын

    This just blowed my mind!!! Love this

  • @apanapane
    @apanapane5 жыл бұрын

    That was beautiful. Thank you.

  • @snatchngrab8262
    @snatchngrab82623 жыл бұрын

    The world needs more teachers like you. I'm more impressed by your teaching skills than any math. Much respect.

  • @jdsingh3607
    @jdsingh36075 жыл бұрын

    Now this video makes me like algebra

  • @FermionClasses

    @FermionClasses

    3 жыл бұрын

    kzread.info/dash/bejne/ioxmpqtydZTghps.html

  • 5 жыл бұрын

    This was fantastic. I wish to thank you for your videos.

  • @mathstraining6996
    @mathstraining69965 жыл бұрын

    Really good video. Thanks for inspiring students. Keep it up

  • @almightyhydra
    @almightyhydra5 жыл бұрын

    3:20 just put y = x^2 + 3x, then you have y(y+2) + 1 = y^2 + 2y + 1 = (y+1)^2. So the answer is y + 1, or x^2 + 3x + 1.

  • @cypherx7247

    @cypherx7247

    5 жыл бұрын

    I also did it in this way...but that way was also fine...its all about which method comes in your head first

  • @lasergamer2869

    @lasergamer2869

    3 жыл бұрын

    Dang that’s genius

  • @eannacoleman957
    @eannacoleman9572 жыл бұрын

    I love the explanation, though I did it a bit differently. When I got to the second line, I substituted (x²+3x) as y and found that that worked much simpler than distributing 2 as 1+1.

  • @star_ms
    @star_ms2 жыл бұрын

    Seemingly elementary problems can have wonderfully elegant solutions! All we need is to substitute a number with x, and the magic begins.

  • @bucinoulje7505
    @bucinoulje75053 жыл бұрын

    i watched this video this video right before my math competition and the same type of question came up on the task sheet. Thank you very much!

  • @bucinoulje7505

    @bucinoulje7505

    3 жыл бұрын

    for those wondering the question was 202120212019(202120212021)(202120212023) all over 100010001 x (202120212021 squared +4)

  • @DavidS-qn3jm
    @DavidS-qn3jm5 жыл бұрын

    I did assume there was a nice solution, but expanding under the root to get x^4 + 6x^3 + 11x^2 + 6x + 1 was pretty easy, and then matching coefficients in (x^2 + ax + 1)^2 was straightforward too. But yeah, the main thing is to replace 500 by x. I don't think I could intuitively see which two of the brackets would make it easier, and I'm not sure that's a better method than expanding the whole thing to only 4 terms (plus the one on the outside).

  • @aikenkazim5318
    @aikenkazim53185 жыл бұрын

    please give an example differentiation of complex functions

  • @zoroarklover363
    @zoroarklover3635 жыл бұрын

    I love you, you make me remember stuff I had forgotten!

  • @kartikeyasingh8592
    @kartikeyasingh85923 жыл бұрын

    You are an absolute genius bro🤟🤟 I was surprised by your last step result 😱😱😱

  • @laudine878
    @laudine8785 жыл бұрын

    Doing a PhD in Literary Studies, but stuff like this is why I absolutely love maths ♥

  • @sadeekmuhammadryan4894
    @sadeekmuhammadryan48942 жыл бұрын

    There are things to learn from each of your videos 😁❤️

  • @deadvirgin428

    @deadvirgin428

    5 ай бұрын

    Well yes, that's the point.

  • @balumathtech2022
    @balumathtech20223 жыл бұрын

    Nice... Great method of solving

  • @neetabhojwani9924
    @neetabhojwani99245 жыл бұрын

    Nice video . I learnt a lot

  • @ammardaffa
    @ammardaffa5 жыл бұрын

    I know this kind of the prob, i use (n+1)(n+2)-1

  • @martinepstein9826
    @martinepstein98262 жыл бұрын

    Nice factoring method but it might have taken me a while to spot. Multiplying out and factoring isn't so bad (x - 1)x(x + 1)(x + 2) + 1 = (x^2 - 1)(x^2 + 2x) + 1 = x^4 + 2x^3 - x^2 - 2x + 1 = (x^2 + bx +- 1)^2 = x^4 + 2bx^3 + (b^2 +- 2)x^2 +- 2bx + 1 We see this works if b = 1 and c = -1 so the answer is 501^2 + 501 - 1 = 500^2 + 2*500 + 1 + 500 = 251501

  • @varunkashyap6571
    @varunkashyap65715 жыл бұрын

    Awesome solution to the question

  • @carterwoodson8818
    @carterwoodson88183 жыл бұрын

    @4:15 wow I did not see it coming! Really good thank you!

  • @imadkhan1825
    @imadkhan18255 жыл бұрын

    You can also this as x^2+3x=t and expression would become t(t+2)+1 =(t+1)^2 this que came in practice test for jee last week And guess what i solved that 😎😎😎👍👍

  • @whyit487
    @whyit4875 жыл бұрын

    I love your videos about not using calculators (Like the Wolfram-Alpha video)! They're the best! Keep up the good work! It's nice going back to algebra sometimes...

  • @blackpenredpen

    @blackpenredpen

    5 жыл бұрын

    Why It? Yea me too. I try to mix things up a bit.

  • @ShaunakDesaiPiano
    @ShaunakDesaiPiano11 ай бұрын

    3:32 perhaps an easier method to spot is if you partially expand the brackets so that you end up with (x²+3x)² + 2(x²+3x) + 1, which is precisely (x²+3x+1)²

  • @G_sen_sei
    @G_sen_sei5 жыл бұрын

    Very interesting calculation!

  • @Mothuzad
    @Mothuzad3 жыл бұрын

    Shout-out to my colorblind fam who can never tell when he switches pens

  • @-a5624
    @-a56245 жыл бұрын

    I know this is not related to this video but I wanted to post this on a new video so you might see it :) your trick for integrals of thinking "wouldn't it be nice if..." has helped me so so much, so thank you :) love your videos!

  • @blackpenredpen

    @blackpenredpen

    5 жыл бұрын

    Awww thank you!!!!!

  • @naysay02
    @naysay02 Жыл бұрын

    man this was amazing to watch! so clever!

  • @bernardelmargi9733
    @bernardelmargi97333 жыл бұрын

    This is very useful, I’m trying to think more outside the the box for hard mathematical equations either for proofs or something like this, I didn’t thing to make 500 = x, but it simplified it so much. This is a useful skill and I will be sure to use it

  • @moosemoosington1441
    @moosemoosington14412 жыл бұрын

    Dude, I always had a good grasp on algebra as a kid and in highschool I always aced most algebra, but somehow my teachers (and I) missed this property of algebraic equations. So freaking cool. It has been nigh on 15 years since high school, but I am still learning new and cool algebra. Thanks so much blackpenredpen!

  • @mango417
    @mango4174 жыл бұрын

    "And now, here's the deal"… You know that when he pronounces that phrase things are 'bout to get complicated.

  • @lisamariefan
    @lisamariefan3 жыл бұрын

    Actually trying it out was fun, and there was some surprisingly elegant generalization going on behind the scenes.

  • @kodichandrashekher7213
    @kodichandrashekher72134 жыл бұрын

    It is so interesting and good to remember. Thanks.

  • @noverdy
    @noverdy5 жыл бұрын

    Everybody know e^2.pi.i = 1 . . But I know 1 = e^2.pi.i

  • @mundane3809

    @mundane3809

    5 жыл бұрын

    Wrong it's - (e ^ pi × i)

  • @nikolas9105

    @nikolas9105

    5 жыл бұрын

    @@mundane3809 Nice try but thats -1 ignoring your name

  • @mundane3809

    @mundane3809

    5 жыл бұрын

    @@nikolas9105 no e ^ ( pi × i ) = -1 So if you make -1 negative, it become positive.

  • @RunstarHomer

    @RunstarHomer

    5 жыл бұрын

    @@mundane3809 you are correct but the original comment was also correct. e^2πi = 1.

  • @mundane3809

    @mundane3809

    5 жыл бұрын

    @@RunstarHomer oof yea it's actually correct. sorry for the mistake!

  • @enzoTHEferrari
    @enzoTHEferrari5 жыл бұрын

    I understood everything until the bit at 4:35 - 5:04 What do you mean by "factoring out"?

  • @AE-rg5rc

    @AE-rg5rc

    5 жыл бұрын

    When a number repeats itself in an addition you can factor it out, basically do the inverse of distributive property. So we have x²+3x+1 repeating in both therms. You can factor it out and you will be left with x²+3x+1 ( x²+3x +1), equivalent to x²+3x+1( x²+3x) + x²+3x+1 (1)

  • @leif1075

    @leif1075

    5 жыл бұрын

    @@AE-rg5rc but thats just squaring it and you don't have two of the sake expression..you don't jave twobx squared plus 3x plus 2 you only,have one

  • @ViratKohli-jj3wj

    @ViratKohli-jj3wj

    4 жыл бұрын

    @@leif1075 please Learn some math, this is for grade 6 atleast in asian countries.

  • @leif1075

    @leif1075

    4 жыл бұрын

    @@ViratKohli-jj3wj I know some math, thanks very much..I had a valid question

  • @yannisdekonoha
    @yannisdekonoha2 жыл бұрын

    When he drops the "Check this out", you know crazy stuff will happen on the board

  • @SpongeDude8
    @SpongeDude85 жыл бұрын

    More impressed with how someone came up with the question

  • @hellopeter121
    @hellopeter1215 жыл бұрын

    What Everybody knows : 1+1=2 What BPRP knows : 2=1+1 . . . . . What I know : 1+1=2 and 2=1+1 😇😇😇😇😇😇😇😇😇😇😇

  • @kinyutaka
    @kinyutaka5 жыл бұрын

    I'm doing this on the toilet, so I only hope I'm starting correctly, with (500)(502)=(501²-1) and (501)(503)=(502²-1) But then again, we could cheat and go with (501)(502)=(501½²-¼) and (500)(503)=(501½²-9/4)?

  • @smragibrezwan2778
    @smragibrezwan27785 жыл бұрын

    WOW! Now that's an amazing way to solve it!

  • @vudomath
    @vudomath4 жыл бұрын

    At 3:45, you could also treat the first factor as (x^2+3x+1-1) so together with the second factor you have (x^2+3x+1-1)(x^2+3x+1+1) = difference of squares ((x^2+3x+1)^2 - 1. Plus the extra 1 on the outside you get the perfect square.

  • @LiegeNorth
    @LiegeNorth3 жыл бұрын

    this guy is a genius!

  • @ishmeetsingh1146
    @ishmeetsingh11465 жыл бұрын

    Wow your method and my method are similar .....I had take the whole expression as y and then square it and then assume x to be 500 and multiplied and had taken x^2+3x to be z and at end I got y=z+1 that is y = x^2 + 3x + 1 and it's done

  • @AdityaTiwari-wf2gi
    @AdityaTiwari-wf2gi5 жыл бұрын

    Brilliant solution .keep it up

  • @science-y9209
    @science-y92093 жыл бұрын

    This was a great explanation

  • @DarkRedZane
    @DarkRedZane3 жыл бұрын

    I have never been so hyped at 2 = 1+1 before.

  • @mdaslamhayat627
    @mdaslamhayat6275 жыл бұрын

    Why I shouldn't belive my calculator? It gave me the answer as 251501 Edit: I never had that much likes in my life

  • @aifesolenopsisgomez605

    @aifesolenopsisgomez605

    5 жыл бұрын

    but... was it fun?

  • @JohnSmith-kb4re

    @JohnSmith-kb4re

    5 жыл бұрын

    @@aifesolenopsisgomez605 Fun is not something one considers when wrestling with numbers, but this... Does put a smile on my face.

  • @Meteo_sauce

    @Meteo_sauce

    5 жыл бұрын

    Because in exams, you get your marks based on working and not on the answer

  • @matbronk1

    @matbronk1

    5 жыл бұрын

    I think he meant that algebra is more useful than a calculator. The title doesn't read "you shouldn't believe your calculator", it says you shouldn't believe IN your calculator, and rather resort to algebra instead.

  • @mdaslamhayat627

    @mdaslamhayat627

    5 жыл бұрын

    LOL, Wasn't expecting that much comments, sure algebra is better than directly using calculator and is more enjoyable to do so , but it took me time to realize what he meant. Besides, I am a 7th grader, so calculator is not allowed in school for us. We can use from 9th grade.

  • @arkabhattacharya1792
    @arkabhattacharya17922 жыл бұрын

    The entry was epic and the whole video is interesting.

  • @sadanandbhushan6713
    @sadanandbhushan67134 жыл бұрын

    Thank u very much i couldn't ever solve it without ur help...and i like the way you analize and explain every Q. In such away that a child also can find it helping...and i got ur ans.. Bro🙏

  • @alexsandroagustini714
    @alexsandroagustini7143 жыл бұрын

    Him: Starts the video with 1+1=2 Me: *ok we are getting somewhere now

  • @Kino-Imsureq
    @Kino-Imsureq5 жыл бұрын

    BPRP know 2 = 1+1 I know 2 = 2 what happened to the comment button its gray

  • @jinja3113

    @jinja3113

    5 жыл бұрын

    I know 2 = two

  • @PedroMartins-ux7mv
    @PedroMartins-ux7mv3 жыл бұрын

    Very elegant solution

  • @jcb3393
    @jcb33933 жыл бұрын

    I did it by recognizing that (x^2+3x)(x^2+3x+2) is easily simplified with a substitution of y=(x^2+3x+1). It simplifies to (y-1)(y+1) = y^2 - 1. Since we have a "+1" hanging out after the 4-term product, that gets rid of the "-1" in our simplified expression, yielding just y^2 under the radical sign. square root of y^2 = y. That means the solution is our substitution: y=(x^2+3x+1). Plugging in 500 for x gives us 251501.

  • @GodzillaFreak
    @GodzillaFreak5 жыл бұрын

    Just do the multiplication by hand.

  • @dev.imperatus6105
    @dev.imperatus61055 жыл бұрын

    Hmmm ive got an easier way when you use 1 + 1 instead of 2 Here is how I do according to you: (x^2+3x+2)(x^2+3x+1) =(x^2+3x)^2 +2 then √((x^2+3x)^2 +2) = x^2+3x+1

  • @XWurstbrotX

    @XWurstbrotX

    5 жыл бұрын

    You can't solve squareroots of sums like that, eventhought your result is correct.

  • @UberPretzel101996
    @UberPretzel1019965 жыл бұрын

    Man, you deserve more subs!

  • @Rishith198
    @Rishith198Ай бұрын

    wow, just wow!! Fascinating !!