80=(3)(x+6)(x+6)

Solution for 80=(3)(x+6)(x+6) equation:

Simplifying
80 = (3)(x + 6)(x + 6)

Reorder the terms:
80 = 3(6 + x)(x + 6)

Reorder the terms:
80 = 3(6 + x)(6 + x)

Multiply (6 + x) * (6 + x)
80 = 3(6(6 + x) + x(6 + x))
80 = 3((6 * 6 + x * 6) + x(6 + x))
80 = 3((36 + 6x) + x(6 + x))
80 = 3(36 + 6x + (6 * x + x * x))
80 = 3(36 + 6x + (6x + x2))

Combine like terms: 6x + 6x = 12x
80 = 3(36 + 12x + x2)
80 = (36 * 3 + 12x * 3 + x2 * 3)
80 = (108 + 36x + 3x2)

Solving
80 = 108 + 36x + 3x2

Solving for variable 'x'.

Combine like terms: 80 + -108 = -28
-28 + -36x + -3x2 = 108 + 36x + 3x2 + -108 + -36x + -3x2

Reorder the terms:
-28 + -36x + -3x2 = 108 + -108 + 36x + -36x + 3x2 + -3x2

Combine like terms: 108 + -108 = 0
-28 + -36x + -3x2 = 0 + 36x + -36x + 3x2 + -3x2
-28 + -36x + -3x2 = 36x + -36x + 3x2 + -3x2

Combine like terms: 36x + -36x = 0
-28 + -36x + -3x2 = 0 + 3x2 + -3x2
-28 + -36x + -3x2 = 3x2 + -3x2

Combine like terms: 3x2 + -3x2 = 0
-28 + -36x + -3x2 = 0

Factor out the Greatest Common Factor (GCF), '-1'.
-1(28 + 36x + 3x2) = 0

Ignore the factor -1.
Subproblem 1
Set the factor '(28 + 36x + 3x2)' equal to zero and attempt to solve:

Simplifying
28 + 36x + 3x2 = 0

Solving
28 + 36x + 3x2 = 0

Begin completing the square.  Divide all terms by
3 the coefficient of the squared term: 

Divide each side by '3'.
9.333333333 + 12x + x2 = 0

Move the constant term to the right:

Add '-9.333333333' to each side of the equation.
9.333333333 + 12x + -9.333333333 + x2 = 0 + -9.333333333

Reorder the terms:
9.333333333 + -9.333333333 + 12x + x2 = 0 + -9.333333333

Combine like terms: 9.333333333 + -9.333333333 = 0.000000000
0.000000000 + 12x + x2 = 0 + -9.333333333
12x + x2 = 0 + -9.333333333

Combine like terms: 0 + -9.333333333 = -9.333333333
12x + x2 = -9.333333333

The x term is 12x.  Take half its coefficient (6).
Square it (36) and add it to both sides.

Add '36' to each side of the equation.
12x + 36 + x2 = -9.333333333 + 36

Reorder the terms:
36 + 12x + x2 = -9.333333333 + 36

Combine like terms: -9.333333333 + 36 = 26.666666667
36 + 12x + x2 = 26.666666667

Factor a perfect square on the left side:
(x + 6)(x + 6) = 26.666666667

Calculate the square root of the right side: 5.163977795

Break this problem into two subproblems by setting 
(x + 6) equal to 5.163977795 and -5.163977795.

Subproblem 1
x + 6 = 5.163977795

Simplifying
x + 6 = 5.163977795

Reorder the terms:
6 + x = 5.163977795

Solving
6 + x = 5.163977795

Solving for variable 'x'.

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

Add '-6' to each side of the equation.
6 + -6 + x = 5.163977795 + -6

Combine like terms: 6 + -6 = 0
0 + x = 5.163977795 + -6
x = 5.163977795 + -6

Combine like terms: 5.163977795 + -6 = -0.836022205
x = -0.836022205

Simplifying
x = -0.836022205

Subproblem 2
x + 6 = -5.163977795

Simplifying
x + 6 = -5.163977795

Reorder the terms:
6 + x = -5.163977795

Solving
6 + x = -5.163977795

Solving for variable 'x'.

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

Add '-6' to each side of the equation.
6 + -6 + x = -5.163977795 + -6

Combine like terms: 6 + -6 = 0
0 + x = -5.163977795 + -6
x = -5.163977795 + -6

Combine like terms: -5.163977795 + -6 = -11.163977795
x = -11.163977795

Simplifying
x = -11.163977795

Solution
The solution to the problem is based on the solutions
from the subproblems.
x = {-0.836022205, -11.163977795}
Solution
x = {-0.836022205, -11.163977795}