# What is the vertex form of y= x^2 + 4x -21 ?

Mar 24, 2016

In vertex form ; $y = {\left(x + 2\right)}^{2} - 25$

#### Explanation:

$y = {x}^{2} + 4 x - 21 \mathmr{and} y = {x}^{2} + 4 x + 4 - 25 \mathmr{and} y = {\left(x + 2\right)}^{2} - 25$ Here vertex is at (-2,-25) graph{x^2+4x-21 [-80, 80, -40, 40]}[Ans]