Question

What is the vertex of g(x) = 3x2 − 12x + 7?

(−6, −5)
(−2, −5)
(2, −5)
(6, −5)

Answer 1

c,

Explanation:

Answer 2

(2, -5)

Explanation:

Convert to vertex form:

3x^2 - 12x + 7

= 3(x^2 - 4x) + 7

Completing the square:

= 3[ (x - 2)^2 - 4)] + 7

= 3(x - 2)^2 - 12 + 7

= 3(x - 2)^2 - 5.

Comparing with the general form

a(x - b)^2 + c we see that the vertex is (b, c) = (2, -5).