Question

A quadratic curve passes through the points (-4, 12) and (0, 8).

The equation of the curve is y = x^2+kx+8.
Find the value of k.

Answer 1

k = 3

Explanation:

Since the curve passes through (- 4, 12) and (0, 8) then the coordinates of these points make the equation true.

Substitute (- 4, 12) into the equation and solve for k, that is

(- 4)² + (- 4)k + 8 = 12

16 - 4k + 8 = 12

24 - 4k = 12 ( subtract 24 from both sides )

- 4k = - 12 ( divide both sides by - 4 )

k = 3