-2x^2+6x+12=0

Solution for -2x^2+6x+12=0 equation:

Simplifying
-2x2 + 6x + 12 = 0

Reorder the terms:
12 + 6x + -2x2 = 0

Solving
12 + 6x + -2x2 = 0

Solving for variable 'x'.

Factor out the Greatest Common Factor (GCF), '2'.
2(6 + 3x + -1x2) = 0

Ignore the factor 2.
Subproblem 1
Set the factor '(6 + 3x + -1x2)' equal to zero and attempt to solve:

Simplifying
6 + 3x + -1x2 = 0

Solving
6 + 3x + -1x2 = 0

Begin completing the square.  Divide all terms by
-1 the coefficient of the squared term: 

Divide each side by '-1'.
-6 + -3x + x2 = 0

Move the constant term to the right:

Add '6' to each side of the equation.
-6 + -3x + 6 + x2 = 0 + 6

Reorder the terms:
-6 + 6 + -3x + x2 = 0 + 6

Combine like terms: -6 + 6 = 0
0 + -3x + x2 = 0 + 6
-3x + x2 = 0 + 6

Combine like terms: 0 + 6 = 6
-3x + x2 = 6

The x term is -3x.  Take half its coefficient (-1.5).
Square it (2.25) and add it to both sides.

Add '2.25' to each side of the equation.
-3x + 2.25 + x2 = 6 + 2.25

Reorder the terms:
2.25 + -3x + x2 = 6 + 2.25

Combine like terms: 6 + 2.25 = 8.25
2.25 + -3x + x2 = 8.25

Factor a perfect square on the left side:
(x + -1.5)(x + -1.5) = 8.25

Calculate the square root of the right side: 2.872281323

Break this problem into two subproblems by setting 
(x + -1.5) equal to 2.872281323 and -2.872281323.

Subproblem 1
x + -1.5 = 2.872281323

Simplifying
x + -1.5 = 2.872281323

Reorder the terms:
-1.5 + x = 2.872281323

Solving
-1.5 + x = 2.872281323

Solving for variable 'x'.

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

Add '1.5' to each side of the equation.
-1.5 + 1.5 + x = 2.872281323 + 1.5

Combine like terms: -1.5 + 1.5 = 0.0
0.0 + x = 2.872281323 + 1.5
x = 2.872281323 + 1.5

Combine like terms: 2.872281323 + 1.5 = 4.372281323
x = 4.372281323

Simplifying
x = 4.372281323

Subproblem 2
x + -1.5 = -2.872281323

Simplifying
x + -1.5 = -2.872281323

Reorder the terms:
-1.5 + x = -2.872281323

Solving
-1.5 + x = -2.872281323

Solving for variable 'x'.

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

Add '1.5' to each side of the equation.
-1.5 + 1.5 + x = -2.872281323 + 1.5

Combine like terms: -1.5 + 1.5 = 0.0
0.0 + x = -2.872281323 + 1.5
x = -2.872281323 + 1.5

Combine like terms: -2.872281323 + 1.5 = -1.372281323
x = -1.372281323

Simplifying
x = -1.372281323

Solution
The solution to the problem is based on the solutions
from the subproblems.
x = {4.372281323, -1.372281323}
Solution
x = {4.372281323, -1.372281323}