(x^2+3x)-3(x^2+3x)-2=0

Solution for (x^2+3x)-3(x^2+3x)-2=0 equation:

Simplifying
(x2 + 3x) + -3(x2 + 3x) + -2 = 0

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

Remove parenthesis around (3x + x2)
3x + x2 + -3(x2 + 3x) + -2 = 0

Reorder the terms:
3x + x2 + -3(3x + x2) + -2 = 0
3x + x2 + (3x * -3 + x2 * -3) + -2 = 0
3x + x2 + (-9x + -3x2) + -2 = 0

Reorder the terms:
-2 + 3x + -9x + x2 + -3x2 = 0

Combine like terms: 3x + -9x = -6x
-2 + -6x + x2 + -3x2 = 0

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

Solving
-2 + -6x + -2x2 = 0

Solving for variable 'x'.

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

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

Simplifying
1 + 3x + x2 = 0

Solving
1 + 3x + x2 = 0

Begin completing the square.

Move the constant term to the right:

Add '-1' to each side of the equation.
1 + 3x + -1 + x2 = 0 + -1

Reorder the terms:
1 + -1 + 3x + x2 = 0 + -1

Combine like terms: 1 + -1 = 0
0 + 3x + x2 = 0 + -1
3x + x2 = 0 + -1

Combine like terms: 0 + -1 = -1
3x + x2 = -1

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 + 2.25

Reorder the terms:
2.25 + 3x + x2 = -1 + 2.25

Combine like terms: -1 + 2.25 = 1.25
2.25 + 3x + x2 = 1.25

Factor a perfect square on the left side:
(x + 1.5)(x + 1.5) = 1.25

Calculate the square root of the right side: 1.118033989

Break this problem into two subproblems by setting 
(x + 1.5) equal to 1.118033989 and -1.118033989.

Subproblem 1
x + 1.5 = 1.118033989

Simplifying
x + 1.5 = 1.118033989

Reorder the terms:
1.5 + x = 1.118033989

Solving
1.5 + x = 1.118033989

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 = 1.118033989 + -1.5

Combine like terms: 1.5 + -1.5 = 0.0
0.0 + x = 1.118033989 + -1.5
x = 1.118033989 + -1.5

Combine like terms: 1.118033989 + -1.5 = -0.381966011
x = -0.381966011

Simplifying
x = -0.381966011

Subproblem 2
x + 1.5 = -1.118033989

Simplifying
x + 1.5 = -1.118033989

Reorder the terms:
1.5 + x = -1.118033989

Solving
1.5 + x = -1.118033989

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 = -1.118033989 + -1.5

Combine like terms: 1.5 + -1.5 = 0.0
0.0 + x = -1.118033989 + -1.5
x = -1.118033989 + -1.5

Combine like terms: -1.118033989 + -1.5 = -2.618033989
x = -2.618033989

Simplifying
x = -2.618033989

Solution
The solution to the problem is based on the solutions
from the subproblems.
x = {-0.381966011, -2.618033989}
Solution
x = {-0.381966011, -2.618033989}