How do you solve x^2 + 8x + 16 = 9?

Feb 27, 2017

$x = - 1$ or $x = - 7$

Explanation:

${x}^{2} + 8 x + 16 = 9$

Subtract $9$ from both sides.

${x}^{2} + 8 x + 7 = 0$

Factorise.

${x}^{2} + 7 x + x + 7 = 0$

$x \left(x + 7\right) + 1 \left(x + 7\right) = 0$

$\left(x + 1\right) \left(x + 7\right) = 0$

$x + 1 = 0$ and $x + 7 = 0$

$x = - 1$ and $x = - 7$