In video I explain what we mean by roots and the discriminant of a quadratic equation.

How the discriminant tells us how many roots a quadratic equation has and the relationship of a quadratic graph to the number of roots based on how it cuts the x-axis.

## Common types of questions on the discriminant

MohammedOctober 21, 2016 at 3:40 pmFor the first question, how did we know that the only root was 1/2?

NostalgiaOctober 23, 2016 at 10:31 amThe square root of 0 is 0. Therefore we get 4 +- 0 / 8 (all over 8 – we get 8 by 2 x 4).

Simplifying 4 / 8 gives us 1 / 2.

Hope that helps.

JoDecember 5, 2016 at 12:03 pmDifficulter question pls

Isaiah GittensNovember 28, 2016 at 9:51 pmGreat video! Helped me a lot!

jade mayaFebruary 8, 2017 at 11:38 amhow did you get x=-3 in question 2

Stuart the ExamSolutions GuyFebruary 8, 2017 at 2:09 pmIf k=9

then if y=x^2+6x+9 then when x=-3, y=0 which is where it touches the x-axis.