Whoops, at 5:51 I display two solutions for an equation, one positive and one negative, but the negative solution actually does not work because you can't take the log of a negative number! So only the positive solution works there, sorry for any confusion caused.

@justabunga1

4 жыл бұрын

Professor Dave Explains there is also one mistake at the very end of the video at 6:23 for ln(x+1)^2=2. There should be two answers, which is -1 plus or minus e. The negative sign comes from the one when you take the square root of both sides. When you plug in -1-e in the original equation, squaring the negative value will still yield positive answer. For example, (-1)^2=1 and 1^2=1. In case you didn’t see the properties of logarithms of the even powers, it would be ln(x+1)^2=2ln(abs(x+1)). abs stands for absolute value. The absolute value is there because the value can be negative at that value. If there’s no absolute value there, it would make the answer undefined.

@Ni999

3 жыл бұрын

log₂(-1) = log₂(-1×1)=log₂(-1)+log₂(1) log₂(-1)+log₂(-4)=log₂(-1×-4)=log₂(4)=2 log₂(-1)+log₂(-4)= log₂(-1)+log₂(1) + log₂(-1)+log₂(4) = log₂(-1×-1)+log₂(1)+log₂(4)=2

@nomthandazohathlani2115

3 жыл бұрын

Hie to my teacher

@hassanruben1019

3 жыл бұрын

I guess it is kind of randomly asking but does anybody know of a good website to watch new series online?

@kyngronin2442

3 жыл бұрын

@Hassan Ruben I dunno I would suggest Flixportal. you can find it on google =) -kyng

profesor dave's intro is what gives me hope.

POV: you just wanna learn logarithmics, and you met jesus christ instead.

@resident1123

3 ай бұрын

Pov pov pov cells pov Jesus interlinked pov cells interlinked pov pov

@resident1123

3 ай бұрын

Pov that feelings when your just wanted to know more logarithmische in mathimatik but instead meeting Jesus the messiah!😂😂

@starGirl-dl1rx

21 күн бұрын

Wow, that's not a good comment. 👎

I literally stopped going to my coaching institute and I feel I learn more from you, thanks professor dave!

Thank you so much for ur vids i didn't take maths in my 11th grade so learning these concepts will help me alot to understand some parts in physics and chemistry 😀❤️

"And if we stare at this for a few seconds, we can see..." 5:41 😂🤣🤣, awesome technique: stare at equations. This is the best part of the video. Your videos are awesome Professor Dave!

@Lee-pf9fl

3 жыл бұрын

And I literally did it🤦‍♀️🤦‍♀️

This video was very fun to follow along with, got to practice some log

Great explanation and engaging graphics! Good job, Professor Dave!

Thanks professor

Thanks prof

what is the definition of a logarithm that makes 2 square or 4 = x square - 3x , how did you get the 4

At 5:50 x cannot be -1 since log2 (-1) is undefined for negative values of x.

@ProfessorDaveExplains

6 жыл бұрын

ah mannnn! yeah. you're totally right. thanks for pointing that out.

@bao5860

5 жыл бұрын

​@@ProfessorDaveExplains it's strange because when we compensate (-1) in the second expression after we condensed it, it's fine! but in the first expression (expanded) it's not valid as Teen pointed out.

@MarkJashierSetosta

2 жыл бұрын

Is this called as Critical Numbers?

Logarithm made simple thank you sir.

Bro you are insanely clever teacher thanks for every thing (I like the way you teach)

Well done teacher

youre my hero bro

can someone explain to me if a question: logx 4³ - logx 2 = 5?

wouldn't -1 be extraneous?

I'm kinda desperate now because my quiz in this subject will be tomorrow and Professor Dave explained it in detail. Thanks, Jesus

@sadiewest1867

3 жыл бұрын

Same here, I’ve had a sub the past month and she’s really old and had to teach us this. Made no sense, and of course I’m only gonna try and actually learn it last minute now

Hi professor, Can I also use the common log in the place of the natural log in problem number 4??

@camjack1221

9 ай бұрын

no you can't, you can think of ln (log natural) as log e (x) so to cancel it out you need to use e e log e (x) = x

Professor, in 6:29 I didn't understand the solution of ln(x+1)^2=2 can you please explain it? Thank you

@justabunga1

4 жыл бұрын

The answer actually has two solutions because when you take the square root of both sides, you get answers. It should be -1 plus or minus e. ln stands for natural logarithm, which is the short for log base e. There are two that you can do that. The first method is to change this in exponential form, which (x+1)^2=e^2. Now take the square root of both sides with the plus or minus sign, which is x+1=plus or minus e. Therefore p, the answer is -1 pus or minus e. The second method is to use properties of logarithms. ln(x+1)^2=2ln(abs(x+1)). Notice that there is absolute value here because when you square the answer whether it’s positive or negative, the result will still yield the positive value. Divide both sides by 2. You have ln(abs(x+1))=1. Put this is exponential form, which is abs(x+1)=e. Remove the absolute by taking plus or minus sign on the right hand side, which is x+1=plus or minus e. Therefore, the answer is -1 plus or minus e.

What is the solution of 9^2x-1 =36x

explanation as lucid as clear running water

When we use ln and log Mr. Dave..?

@justabunga1

4 жыл бұрын

You can use either one as long as the base are the same. On your calculator, we only have common log (log base 10) and natural log (log base e). A logarithm without a subscript is referred to a common log (written as “log” on your calculator). log base e of x is the same as natural log (ln). Usually, we use ln only if the base is e and common log if the base is 10.

What does that "In" mean??

@ProfessorDaveExplains

6 жыл бұрын

natural log! check out the three part series i did on logarithms that was released just before this one.

@MiltosPol-qn3zh

6 жыл бұрын

Professor Dave Explains Thanks

@tc-01-client56

6 жыл бұрын

MILTIADIS POLITIS It's the natural logarithm. Basically, log to the base of e.

why your video can't be download

For the comprehension problems, how did you get from log(3x-2)=1 to 10=(3x-2)? Did you apply log base 10 to both sides of the equation?

@ProfessorDaveExplains

5 жыл бұрын

it's just the definition of a log, the base of the log raised to the power of what's on the other side of the equals sign is equivalent to what the log is operating on.

@justabunga1

4 жыл бұрын

If there’s no subscript written in the logarithmic form, it refers to the common log or log base 10.

@phewpheww4599

2 жыл бұрын

@@ProfessorDaveExplains why is log 1 euqals to 0 but 10 in this equation?

@bathtubanarchy

Жыл бұрын

​@@phewpheww4599 ​ there's a few parts to this answer. log(1) does = 0. Log(1) = x is asking you to find what number, if the base 10 was raised by this number, would be equal to 1? By the laws of exponents, any number raised to 0 will equal 1. Any base log will do the same. Log3(1) =0, log999(1) = 0. The answer to the third question, log(3x-2) = 1, has nothing to do with that rule. The 1 is already equal to the left side of the equation, the question is not asking you to find out what log(1) = x is. In the third question, we can express the 1 on the right as log(10), so it has the same base as the left side. Because log10(10) is equal to one, log(10) can be substituted for 1. To confirm that, solve log10(10) = x, which is asking by what number 10 needs to be raised by to equal 10. 10^1 = 10, so the answer is 1. Then we have log(3x-2) = log(10). As we have log on both sides, they can be cancelled out, leaving 3x-2 = 10. Balance by adding 2 to both sides. 3x = 12. Divide by 3. X = 4. I could be wrong but that's how I understand it.

in the last question of the comprehension, it can be (-e -1) as well

@designingworld6611

3 жыл бұрын

yes you're right👍

I need help I need to find the answer to 5^(2x-3)=11 using ln but idk how to

@justabunga1

4 жыл бұрын

Take ln of both sides, which is ln(5^(2x-3))=ln(11). Use the properties to bring the exponent down as a coefficient. (2x-3)ln(5)=ln(11). Divide both sides by ln(5) and add 3 then divide the whole answer by 2, which is (ln(11)/ln(5)+3)/2. If you want a more clear and exact answer, it would be (log_5(11)+3)/2. log_5(11) is log base 5 of 11. You can try this on your calculator if you want an approximate answer.

ty professor jesus

@chuksdagamer6523

3 жыл бұрын

what?

I’m actually gonna cry rn

i understood his explanation and such but i couldnt answer the reading comprehension oh my gosh my calculus exam is tom. and its now 12 am midnigbt

@ProfessorDaveExplains

4 жыл бұрын

Well this isn't even calculus, it's algebra, so it sounds like you might be in a lot of trouble!

@paenk976

4 жыл бұрын

@@ProfessorDaveExplains omggg reallyyy aa but why is this whatmy calculus teacher lectured to us

@ProfessorDaveExplains

4 жыл бұрын

I dunno what to tell you, this isn't calculus.

@paenk976

4 жыл бұрын

@@ProfessorDaveExplains i just got home from school and i just finished the exam! this video of yours actually helped tho even if the exam was calculus skskksks

@ProfessorDaveExplains

4 жыл бұрын

Well, that's good news then! Make sure to keep watching through my mathematics playlist so that you're never in trouble again!

All was good until I had to solve them yikes

How can I support you at patreon sir?

@ProfessorDaveExplains

3 жыл бұрын

Just click here and pledge what you wish! www.patreon.com/professordaveexplains

@gardenmenuuu

3 жыл бұрын

Words cant explain how you have helped me thanks so much

Last solution in comprehension section was pretty sipid. I only enjoy math when I understand it.

4:04

3:17

wow

Done.

The last equation of the comprehension Check is wrong ist should be x = e^root(2) -1

@ProfessorDaveExplains

2 жыл бұрын

The video is correct.

👍👍

The way you've taught this is as if a person already knows certain things... If I am watching this video.... Chances are I don't know the steps that you've assumed I know.

@ProfessorDaveExplains

7 ай бұрын

Then go back earlier in the math series.

how about this? 4^x + 4^x+1 = 40

@ProfessorDaveExplains

6 жыл бұрын

take log base 4!

What is the "in" please care to explain

@ProfessorDaveExplains

Ай бұрын

ln is natural log, go to the tutorials earlier in the series explaining logs

@DA_FAMAS_RUK

Ай бұрын

Thank you didn't expected you

@ajoybiswas9180

Ай бұрын

😮

@ajoybiswas9180

Ай бұрын

​@@ProfessorDaveExplainssir which video please 🙏 tell

Wait so you don't have to use Bhaskara? You can just stare at it?

Thank you Dave! Our Savior!

cood v

I don't understand the e's you put in the examples. They weren't addressed in the video. So you lost me

math jesus

my teacher hates me

I left a log in my toilet

❤😂🎉😢😮😅😊

You are too fast

@ProfessorDaveExplains

5 жыл бұрын

try setting it to 0.75 speed or even 0.5 speed