# How do you solve x^2 + 7 = 71?

Aug 27, 2016

$x = - 8 \mathmr{and} x = + 8$

#### Explanation:

As this is a quadratic, we would usually make it =0,
But this is a special case where there is no term in x.

#x^2 =71-7

${x}^{2} = 64$

$x = \pm \sqrt{64}$

$x = \pm 8$

We could also have factored as the difference of two squares.

${x}^{2} - 64 = 0$

$\left(x + 8\right) \left(x - 8\right) = 0$

$x = - 8 \mathmr{and} x = + 8$