(12x+4)(x)=36

Solution for (12x+4)(x)=36 equation:

Simplifying
(12x + 4)(x) = 36

Reorder the terms:
(4 + 12x)(x) = 36

Reorder the terms for easier multiplication:
x(4 + 12x) = 36
(4 * x + 12x * x) = 36
(4x + 12x2) = 36

Solving
4x + 12x2 = 36

Solving for variable 'x'.

Reorder the terms:
-36 + 4x + 12x2 = 36 + -36

Combine like terms: 36 + -36 = 0
-36 + 4x + 12x2 = 0

Factor out the Greatest Common Factor (GCF), '4'.
4(-9 + x + 3x2) = 0

Ignore the factor 4.
Subproblem 1
Set the factor '(-9 + x + 3x2)' equal to zero and attempt to solve:

Simplifying
-9 + x + 3x2 = 0

Solving
-9 + x + 3x2 = 0

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

Divide each side by '3'.
-3 + 0.3333333333x + x2 = 0

Move the constant term to the right:

Add '3' to each side of the equation.
-3 + 0.3333333333x + 3 + x2 = 0 + 3

Reorder the terms:
-3 + 3 + 0.3333333333x + x2 = 0 + 3

Combine like terms: -3 + 3 = 0
0 + 0.3333333333x + x2 = 0 + 3
0.3333333333x + x2 = 0 + 3

Combine like terms: 0 + 3 = 3
0.3333333333x + x2 = 3

The x term is x.  Take half its coefficient (0.5).
Square it (0.25) and add it to both sides.

Add '0.25' to each side of the equation.
0.3333333333x + 0.25 + x2 = 3 + 0.25

Reorder the terms:
0.25 + 0.3333333333x + x2 = 3 + 0.25

Combine like terms: 3 + 0.25 = 3.25
0.25 + 0.3333333333x + x2 = 3.25

Factor a perfect square on the left side:
(x + 0.5)(x + 0.5) = 3.25

Calculate the square root of the right side: 1.802775638

Break this problem into two subproblems by setting 
(x + 0.5) equal to 1.802775638 and -1.802775638.

Subproblem 1
x + 0.5 = 1.802775638

Simplifying
x + 0.5 = 1.802775638

Reorder the terms:
0.5 + x = 1.802775638

Solving
0.5 + x = 1.802775638

Solving for variable 'x'.

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

Add '-0.5' to each side of the equation.
0.5 + -0.5 + x = 1.802775638 + -0.5

Combine like terms: 0.5 + -0.5 = 0.0
0.0 + x = 1.802775638 + -0.5
x = 1.802775638 + -0.5

Combine like terms: 1.802775638 + -0.5 = 1.302775638
x = 1.302775638

Simplifying
x = 1.302775638

Subproblem 2
x + 0.5 = -1.802775638

Simplifying
x + 0.5 = -1.802775638

Reorder the terms:
0.5 + x = -1.802775638

Solving
0.5 + x = -1.802775638

Solving for variable 'x'.

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

Add '-0.5' to each side of the equation.
0.5 + -0.5 + x = -1.802775638 + -0.5

Combine like terms: 0.5 + -0.5 = 0.0
0.0 + x = -1.802775638 + -0.5
x = -1.802775638 + -0.5

Combine like terms: -1.802775638 + -0.5 = -2.302775638
x = -2.302775638

Simplifying
x = -2.302775638

Solution
The solution to the problem is based on the solutions
from the subproblems.
x = {1.302775638, -2.302775638}
Solution
x = {1.302775638, -2.302775638}