12x^2+28x-12=0

Solution for 12x^2+28x-12=0 equation:

Simplifying
12x2 + 28x + -12 = 0

Reorder the terms:
-12 + 28x + 12x2 = 0

Solving
-12 + 28x + 12x2 = 0

Solving for variable 'x'.

Factor out the Greatest Common Factor (GCF), '4'.
4(-3 + 7x + 3x2) = 0

Ignore the factor 4.
Subproblem 1
Set the factor '(-3 + 7x + 3x2)' equal to zero and attempt to solve:

Simplifying
-3 + 7x + 3x2 = 0

Solving
-3 + 7x + 3x2 = 0

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

Divide each side by '3'.
-1 + 2.333333333x + x2 = 0

Move the constant term to the right:

Add '1' to each side of the equation.
-1 + 2.333333333x + 1 + x2 = 0 + 1

Reorder the terms:
-1 + 1 + 2.333333333x + x2 = 0 + 1

Combine like terms: -1 + 1 = 0
0 + 2.333333333x + x2 = 0 + 1
2.333333333x + x2 = 0 + 1

Combine like terms: 0 + 1 = 1
2.333333333x + x2 = 1

The x term is 2.333333333x.  Take half its coefficient (1.166666667).
Square it (1.361111112) and add it to both sides.

Add '1.361111112' to each side of the equation.
2.333333333x + 1.361111112 + x2 = 1 + 1.361111112

Reorder the terms:
1.361111112 + 2.333333333x + x2 = 1 + 1.361111112

Combine like terms: 1 + 1.361111112 = 2.361111112
1.361111112 + 2.333333333x + x2 = 2.361111112

Factor a perfect square on the left side:
(x + 1.166666667)(x + 1.166666667) = 2.361111112

Calculate the square root of the right side: 1.536590743

Break this problem into two subproblems by setting 
(x + 1.166666667) equal to 1.536590743 and -1.536590743.

Subproblem 1
x + 1.166666667 = 1.536590743

Simplifying
x + 1.166666667 = 1.536590743

Reorder the terms:
1.166666667 + x = 1.536590743

Solving
1.166666667 + x = 1.536590743

Solving for variable 'x'.

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

Add '-1.166666667' to each side of the equation.
1.166666667 + -1.166666667 + x = 1.536590743 + -1.166666667

Combine like terms: 1.166666667 + -1.166666667 = 0.000000000
0.000000000 + x = 1.536590743 + -1.166666667
x = 1.536590743 + -1.166666667

Combine like terms: 1.536590743 + -1.166666667 = 0.369924076
x = 0.369924076

Simplifying
x = 0.369924076

Subproblem 2
x + 1.166666667 = -1.536590743

Simplifying
x + 1.166666667 = -1.536590743

Reorder the terms:
1.166666667 + x = -1.536590743

Solving
1.166666667 + x = -1.536590743

Solving for variable 'x'.

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

Add '-1.166666667' to each side of the equation.
1.166666667 + -1.166666667 + x = -1.536590743 + -1.166666667

Combine like terms: 1.166666667 + -1.166666667 = 0.000000000
0.000000000 + x = -1.536590743 + -1.166666667
x = -1.536590743 + -1.166666667

Combine like terms: -1.536590743 + -1.166666667 = -2.70325741
x = -2.70325741

Simplifying
x = -2.70325741

Solution
The solution to the problem is based on the solutions
from the subproblems.
x = {0.369924076, -2.70325741}
Solution
x = {0.369924076, -2.70325741}