This video uses the GeoGebra graphing calculator to shows how to find the solutions (roots, x-intercepts, zeros) of quadratic equations - written in standard form.
Recall, the quadratic formula can find all solutions - real or complex - of any quadratic equation. Graphing a quadratic equation allows us to find all real solutions of a quadratic equation. If there are no real solutions to the quadratic equation, the graph of the function will not cross the x-axis. When the x-intercept is the same as the vertex, there will only be one real (repeated) solution.