Question

What is the x-coordinate of the vertex of the parabola whose equation is y = 3x² + 9x?

Answer 1

Answer: -3/2

Explanation:

The axis of symmetry, and thus the x-coordinate of the vertex, is given by
`x=-(b)/(2a)`

So, the answer is
`x=-(9)/(2(3))=\boxed{-(3)/(2)}`