x^2+8x+16=81

Solution for x^2+8x+16=81 equation:

Simplifying
x2 + 8x + 16 = 81

Reorder the terms:
16 + 8x + x2 = 81

Solving
16 + 8x + x2 = 81

Solving for variable 'x'.

Reorder the terms:
16 + -81 + 8x + x2 = 81 + -81

Combine like terms: 16 + -81 = -65
-65 + 8x + x2 = 81 + -81

Combine like terms: 81 + -81 = 0
-65 + 8x + x2 = 0

Factor a trinomial.
(-13 + -1x)(5 + -1x) = 0

Subproblem 1
Set the factor '(-13 + -1x)' equal to zero and attempt to solve:

Simplifying
-13 + -1x = 0

Solving
-13 + -1x = 0

Move all terms containing x to the left, all other terms to the right.

Add '13' to each side of the equation.
-13 + 13 + -1x = 0 + 13

Combine like terms: -13 + 13 = 0
0 + -1x = 0 + 13
-1x = 0 + 13

Combine like terms: 0 + 13 = 13
-1x = 13

Divide each side by '-1'.
x = -13

Simplifying
x = -13
Subproblem 2
Set the factor '(5 + -1x)' equal to zero and attempt to solve:

Simplifying
5 + -1x = 0

Solving
5 + -1x = 0

Move all terms containing x to the left, all other terms to the right.

Add '-5' to each side of the equation.
5 + -5 + -1x = 0 + -5

Combine like terms: 5 + -5 = 0
0 + -1x = 0 + -5
-1x = 0 + -5

Combine like terms: 0 + -5 = -5
-1x = -5

Divide each side by '-1'.
x = 5

Simplifying
x = 5
Solution
x = {-13, 5}