Question

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

Answer 1

Answer: -3/2

Step-by-step explanation:

The axis of symmetry, and thus the x-coordinate of the vertex, is given by $x=-\frac{b}{2a}$

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