Question

Identify the x-intercepts. Justify your answer by showing each step. y=2x^2+3x-20

Answer 1

x = -4 and x = 5/2

Explanation:

x-intercepts when y = 0

So

2x^2 + 3x - 20 = 0

2 * (-20) = -40

-40 = 8 * (-5)

and 8 - 5 = 3

So

2x^2 + 3x - 20 = 0

2x^2 +8x - 5x - 20 = 0

2x(x + 4) - 5(x + 4) = 0

(2x - 5)(x + 4) = 0

2x - 5 = 0; x = 5/2

x + 4 = 0; x = -4

Answer

x = -4 and x = 5/2