Question

If (a,12) is a point on the graph of y=x^2 +x, what is a

Answer 1

a = -4 or 3

Explanation:

(x, y) therefore, with (a, 12) x = a and y = 12

y = x^2 + x

12 = a^2 + a

a^2 + a - 12 = 0 (quadratic equation)

a^2 + 4a - 3a - 12 = 0

a(a+4) - 3(a+4)

(a + 4) (a - 3) = 0

a = -4, 3