Question

What is the x-coordinate of the vertex of the parabola whose equation is `y=3x^2+9x`?

Answer 1

`x_("vertex")=-3/2`

Explanation:

write as:`" " y=3(x^2+3x)`

Consider the 3 from `3x` and apply

`x_("vertex")=(-1/2)xx(+3) = -3/2`