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

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Answer 1 · 2015-06-03T07:20:59

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

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

$color(blue)((x-9) (x+9))= 0$

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

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