Question

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

Answer 1

Answer: x=-1,5.

Step-by-step explanation:

$y=3x^2+9x\\\boxed {x=-\frac{b}{2a} }\\a=3,\ \ \ \ \ b=9.\\x=-\frac{9}{2*3}=-\frac{3}{2}=-1,5.$