Question

Which equation is y = –3x2 – 12x – 2 rewritten in vertex form?

y = –3(x + 2)2 + 10
y = –3(x – 2)2 + 10
y = –3(x + 2)2 – 14
y = –3(x – 2)2 – 2

Answer 1

y = -3(x + 2)^2 + 10.

Explanation:

y = –3x2 – 12x – 2

Divide first 2 terms by -3:

y = -3(x^2 + 4x) - 2 Now complete the square on x^2 + 4x:-

y = -3(x^2 + 4x + 4 - 4) - 2

y = -3[(x + 2)^2 - 4] - 2

y = -3(x + 2)^2 + 12 - 2

y = -3(x + 2)^2 + 10.