-4x(x+3)=6

Solution for -4x(x+3)=6 equation:

Simplifying
-4x(x + 3) = 6

Reorder the terms:
-4x(3 + x) = 6
(3 * -4x + x * -4x) = 6
(-12x + -4x2) = 6

Solving
-12x + -4x2 = 6

Solving for variable 'x'.

Reorder the terms:
-6 + -12x + -4x2 = 6 + -6

Combine like terms: 6 + -6 = 0
-6 + -12x + -4x2 = 0

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

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

Simplifying
3 + 6x + 2x2 = 0

Solving
3 + 6x + 2x2 = 0

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

Divide each side by '2'.
1.5 + 3x + x2 = 0

Move the constant term to the right:

Add '-1.5' to each side of the equation.
1.5 + 3x + -1.5 + x2 = 0 + -1.5

Reorder the terms:
1.5 + -1.5 + 3x + x2 = 0 + -1.5

Combine like terms: 1.5 + -1.5 = 0.0
0.0 + 3x + x2 = 0 + -1.5
3x + x2 = 0 + -1.5

Combine like terms: 0 + -1.5 = -1.5
3x + x2 = -1.5

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 = -1.5 + 2.25

Reorder the terms:
2.25 + 3x + x2 = -1.5 + 2.25

Combine like terms: -1.5 + 2.25 = 0.75
2.25 + 3x + x2 = 0.75

Factor a perfect square on the left side:
(x + 1.5)(x + 1.5) = 0.75

Calculate the square root of the right side: 0.866025404

Break this problem into two subproblems by setting 
(x + 1.5) equal to 0.866025404 and -0.866025404.

Subproblem 1
x + 1.5 = 0.866025404

Simplifying
x + 1.5 = 0.866025404

Reorder the terms:
1.5 + x = 0.866025404

Solving
1.5 + x = 0.866025404

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 = 0.866025404 + -1.5

Combine like terms: 1.5 + -1.5 = 0.0
0.0 + x = 0.866025404 + -1.5
x = 0.866025404 + -1.5

Combine like terms: 0.866025404 + -1.5 = -0.633974596
x = -0.633974596

Simplifying
x = -0.633974596

Subproblem 2
x + 1.5 = -0.866025404

Simplifying
x + 1.5 = -0.866025404

Reorder the terms:
1.5 + x = -0.866025404

Solving
1.5 + x = -0.866025404

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 = -0.866025404 + -1.5

Combine like terms: 1.5 + -1.5 = 0.0
0.0 + x = -0.866025404 + -1.5
x = -0.866025404 + -1.5

Combine like terms: -0.866025404 + -1.5 = -2.366025404
x = -2.366025404

Simplifying
x = -2.366025404

Solution
The solution to the problem is based on the solutions
from the subproblems.
x = {-0.633974596, -2.366025404}
Solution
x = {-0.633974596, -2.366025404}