Question

Write x2 + 4x - 2 in vertex form.

Answer 1

The vertex form: y = a(x - h)² + k

y = ax² + bx + c then h = -b/2a and k = f(h).

y = x² + 4x - 2

a = 1; b = 4; c = -2

h = -4/(2·1) = -4/2 = -2

k = f(-2) = (-2)² + 4·(-2) - 2 = 4 - 8 - 2 = -6

Answer: y = (x + 2)² - 6.