Question

Which of the following describes the parabola with the equation y = −x2 − 3x + 6?

A) The axis of symmetry is x = 1.5 and the vertex is (1.5, 12.75).
B) The axis of symmetry is x = −1 and the vertex is (−1, −3).
C) The axis of symmetry is x = −1.5 and the vertex is (−1.5, 8.25).
D) The axis of symmetry is x = 0 and the vertex is (0, 6).

Answer 1

C) The axis of symmetry is x = −1.5 and the vertex is (−1.5, 8.25).

Explanation:

The axis of symmetry is x = − b/2a

= -(-3) / 2(-1)

= 3/(-2)

= -1.5

the vertex => x = -1.5

y= -(-1.5)²-3(-1.5)+6 =

-2.25 +4.5+6= 8.25