Question

Find the vertex of the quadratic equation: y = 2x2 + 8x − 4

Answer 1

Didn't know this one so I looked it up!

2(x^2 + 4x - 2) = y
x^2 + 4x - 2 = y/2
x^2 + 4x +4 = y/2 + 6

(x+2)^2 = y/2 + 6

(x+2)^2 - 6 = y/2

2(x + 2)^2 - 12 = y

so the vertex is (-2, -12)