Write x2 + 4x - 2 in vertex form.

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.