Question 184449
{{{(x+8)^2 = 81}}}
Square roots come in pairs. There is a (+) and a (-) 
square root.
Take the square root of both sides
{{{x + 8 = 9}}}
{{{x = 1}}}
and
{{{x + 8 = -9}}}
{{{x = -17}}}
The answers are {{{x = 1}}} and {{{x = -17}}}
check answers:
{{{(x+8)^2 = 81}}}
{{{(1+8)^2 = 81}}}
{{{81 = 81}}}
and
{{{(-17+8)^2 = 81}}}
{{{(-9)^2 = 81}}}
{{{81 = 81}}}
OK