# How do you factor and solve x^2=81?

Jun 3, 2015

${x}^{2} = 81$
can be written as
${x}^{2} - 81 = 0$

by property , color(blue)(a^2 - b^2 = (a+b)(a-b)
The expression becomes
${x}^{2} - {\left(9\right)}^{2} = 0$

$\textcolor{b l u e}{\left(x - 9\right) \left(x + 9\right)} = 0$

equating each of the terms with zero we obtain the solution
$x - 9 = 0$
and
$x + 9 = 0$
the solutions are color(blue)( x = 9 or x = -9