# What is the vertex form of y= -3x^2 − 30x-4 ?

Nov 30, 2015

$- 3 {\left(x + 5\right)}^{2} + 71$

#### Explanation:

Factor as follows

$- 3 \left({x}^{2} + 10 x\right) - 4$

Complete the square

$- 3 \left({x}^{2} + 10 x + 25\right) - 4 + 75$

We have to add on $75$. When we distribute the $- 3$, we get $- 3 \left(25\right) = - 75$

Rewrite

$- 3 {\left(x + 5\right)}^{2} + 71$

The vertex is at the point $\left(- 5 , 71\right)$