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

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

Simplifying
0 = 3(x + -2) + 2x(x + 1)

Reorder the terms:
0 = 3(-2 + x) + 2x(x + 1)
0 = (-2 * 3 + x * 3) + 2x(x + 1)
0 = (-6 + 3x) + 2x(x + 1)

Reorder the terms:
0 = -6 + 3x + 2x(1 + x)
0 = -6 + 3x + (1 * 2x + x * 2x)
0 = -6 + 3x + (2x + 2x2)

Combine like terms: 3x + 2x = 5x
0 = -6 + 5x + 2x2

Solving
0 = -6 + 5x + 2x2

Solving for variable 'x'.

Combine like terms: 0 + 6 = 6
6 + -5x + -2x2 = -6 + 5x + 2x2 + 6 + -5x + -2x2

Reorder the terms:
6 + -5x + -2x2 = -6 + 6 + 5x + -5x + 2x2 + -2x2

Combine like terms: -6 + 6 = 0
6 + -5x + -2x2 = 0 + 5x + -5x + 2x2 + -2x2
6 + -5x + -2x2 = 5x + -5x + 2x2 + -2x2

Combine like terms: 5x + -5x = 0
6 + -5x + -2x2 = 0 + 2x2 + -2x2
6 + -5x + -2x2 = 2x2 + -2x2

Combine like terms: 2x2 + -2x2 = 0
6 + -5x + -2x2 = 0

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

Divide each side by '-2'.
-3 + 2.5x + x2 = 0

Move the constant term to the right:

Add '3' to each side of the equation.
-3 + 2.5x + 3 + x2 = 0 + 3

Reorder the terms:
-3 + 3 + 2.5x + x2 = 0 + 3

Combine like terms: -3 + 3 = 0
0 + 2.5x + x2 = 0 + 3
2.5x + x2 = 0 + 3

Combine like terms: 0 + 3 = 3
2.5x + x2 = 3

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 = 3 + 1.5625

Reorder the terms:
1.5625 + 2.5x + x2 = 3 + 1.5625

Combine like terms: 3 + 1.5625 = 4.5625
1.5625 + 2.5x + x2 = 4.5625

Factor a perfect square on the left side:
(x + 1.25)(x + 1.25) = 4.5625

Calculate the square root of the right side: 2.136000936

Break this problem into two subproblems by setting 
(x + 1.25) equal to 2.136000936 and -2.136000936.

Subproblem 1
x + 1.25 = 2.136000936

Simplifying
x + 1.25 = 2.136000936

Reorder the terms:
1.25 + x = 2.136000936

Solving
1.25 + x = 2.136000936

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 = 2.136000936 + -1.25

Combine like terms: 1.25 + -1.25 = 0.00
0.00 + x = 2.136000936 + -1.25
x = 2.136000936 + -1.25

Combine like terms: 2.136000936 + -1.25 = 0.886000936
x = 0.886000936

Simplifying
x = 0.886000936

Subproblem 2
x + 1.25 = -2.136000936

Simplifying
x + 1.25 = -2.136000936

Reorder the terms:
1.25 + x = -2.136000936

Solving
1.25 + x = -2.136000936

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 = -2.136000936 + -1.25

Combine like terms: 1.25 + -1.25 = 0.00
0.00 + x = -2.136000936 + -1.25
x = -2.136000936 + -1.25

Combine like terms: -2.136000936 + -1.25 = -3.386000936
x = -3.386000936

Simplifying
x = -3.386000936

Solution
The solution to the problem is based on the solutions
from the subproblems.
x = {0.886000936, -3.386000936}