-2x(2x+3)=4(x+1)-2

Solution for -2x(2x+3)=4(x+1)-2 equation:

Simplifying
-2x(2x + 3) = 4(x + 1) + -2

Reorder the terms:
-2x(3 + 2x) = 4(x + 1) + -2
(3 * -2x + 2x * -2x) = 4(x + 1) + -2
(-6x + -4x2) = 4(x + 1) + -2

Reorder the terms:
-6x + -4x2 = 4(1 + x) + -2
-6x + -4x2 = (1 * 4 + x * 4) + -2
-6x + -4x2 = (4 + 4x) + -2

Reorder the terms:
-6x + -4x2 = 4 + -2 + 4x

Combine like terms: 4 + -2 = 2
-6x + -4x2 = 2 + 4x

Solving
-6x + -4x2 = 2 + 4x

Solving for variable 'x'.

Reorder the terms:
-2 + -6x + -4x + -4x2 = 2 + 4x + -2 + -4x

Combine like terms: -6x + -4x = -10x
-2 + -10x + -4x2 = 2 + 4x + -2 + -4x

Reorder the terms:
-2 + -10x + -4x2 = 2 + -2 + 4x + -4x

Combine like terms: 2 + -2 = 0
-2 + -10x + -4x2 = 0 + 4x + -4x
-2 + -10x + -4x2 = 4x + -4x

Combine like terms: 4x + -4x = 0
-2 + -10x + -4x2 = 0

Factor out the Greatest Common Factor (GCF), '-2'.
-2(1 + 5x + 2x2) = 0

Ignore the factor -2.
Subproblem 1
Set the factor '(1 + 5x + 2x2)' equal to zero and attempt to solve:

Simplifying
1 + 5x + 2x2 = 0

Solving
1 + 5x + 2x2 = 0

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

Divide each side by '2'.
0.5 + 2.5x + x2 = 0

Move the constant term to the right:

Add '-0.5' to each side of the equation.
0.5 + 2.5x + -0.5 + x2 = 0 + -0.5

Reorder the terms:
0.5 + -0.5 + 2.5x + x2 = 0 + -0.5

Combine like terms: 0.5 + -0.5 = 0.0
0.0 + 2.5x + x2 = 0 + -0.5
2.5x + x2 = 0 + -0.5

Combine like terms: 0 + -0.5 = -0.5
2.5x + x2 = -0.5

The x term is 2.5x.  Take half its coefficient (1.25).
Square it (1.5625) and add it to both sides.

Add '1.5625' to each side of the equation.
2.5x + 1.5625 + x2 = -0.5 + 1.5625

Reorder the terms:
1.5625 + 2.5x + x2 = -0.5 + 1.5625

Combine like terms: -0.5 + 1.5625 = 1.0625
1.5625 + 2.5x + x2 = 1.0625

Factor a perfect square on the left side:
(x + 1.25)(x + 1.25) = 1.0625

Calculate the square root of the right side: 1.030776406

Break this problem into two subproblems by setting 
(x + 1.25) equal to 1.030776406 and -1.030776406.

Subproblem 1
x + 1.25 = 1.030776406

Simplifying
x + 1.25 = 1.030776406

Reorder the terms:
1.25 + x = 1.030776406

Solving
1.25 + x = 1.030776406

Solving for variable 'x'.

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

Add '-1.25' to each side of the equation.
1.25 + -1.25 + x = 1.030776406 + -1.25

Combine like terms: 1.25 + -1.25 = 0.00
0.00 + x = 1.030776406 + -1.25
x = 1.030776406 + -1.25

Combine like terms: 1.030776406 + -1.25 = -0.219223594
x = -0.219223594

Simplifying
x = -0.219223594

Subproblem 2
x + 1.25 = -1.030776406

Simplifying
x + 1.25 = -1.030776406

Reorder the terms:
1.25 + x = -1.030776406

Solving
1.25 + x = -1.030776406

Solving for variable 'x'.

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

Add '-1.25' to each side of the equation.
1.25 + -1.25 + x = -1.030776406 + -1.25

Combine like terms: 1.25 + -1.25 = 0.00
0.00 + x = -1.030776406 + -1.25
x = -1.030776406 + -1.25

Combine like terms: -1.030776406 + -1.25 = -2.280776406
x = -2.280776406

Simplifying
x = -2.280776406

Solution
The solution to the problem is based on the solutions
from the subproblems.
x = {-0.219223594, -2.280776406}
Solution
x = {-0.219223594, -2.280776406}