28-(3x+4x)=2(x+6)x

Solution for 28-(3x+4x)=2(x+6)x equation:

Simplifying
28 + -1(3x + 4x) = 2(x + 6) * x

Combine like terms: 3x + 4x = 7x
28 + -1(7x) = 2(x + 6) * x

Remove parenthesis around (7x)
28 + -1 * 7x = 2(x + 6) * x

Multiply -1 * 7
28 + -7x = 2(x + 6) * x

Reorder the terms:
28 + -7x = 2(6 + x) * x

Reorder the terms for easier multiplication:
28 + -7x = 2x(6 + x)
28 + -7x = (6 * 2x + x * 2x)
28 + -7x = (12x + 2x2)

Solving
28 + -7x = 12x + 2x2

Solving for variable 'x'.

Combine like terms: -7x + -12x = -19x
28 + -19x + -2x2 = 12x + 2x2 + -12x + -2x2

Reorder the terms:
28 + -19x + -2x2 = 12x + -12x + 2x2 + -2x2

Combine like terms: 12x + -12x = 0
28 + -19x + -2x2 = 0 + 2x2 + -2x2
28 + -19x + -2x2 = 2x2 + -2x2

Combine like terms: 2x2 + -2x2 = 0
28 + -19x + -2x2 = 0

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

Divide each side by '-2'.
-14 + 9.5x + x2 = 0

Move the constant term to the right:

Add '14' to each side of the equation.
-14 + 9.5x + 14 + x2 = 0 + 14

Reorder the terms:
-14 + 14 + 9.5x + x2 = 0 + 14

Combine like terms: -14 + 14 = 0
0 + 9.5x + x2 = 0 + 14
9.5x + x2 = 0 + 14

Combine like terms: 0 + 14 = 14
9.5x + x2 = 14

The x term is 9.5x.  Take half its coefficient (4.75).
Square it (22.5625) and add it to both sides.

Add '22.5625' to each side of the equation.
9.5x + 22.5625 + x2 = 14 + 22.5625

Reorder the terms:
22.5625 + 9.5x + x2 = 14 + 22.5625

Combine like terms: 14 + 22.5625 = 36.5625
22.5625 + 9.5x + x2 = 36.5625

Factor a perfect square on the left side:
(x + 4.75)(x + 4.75) = 36.5625

Calculate the square root of the right side: 6.046693311

Break this problem into two subproblems by setting 
(x + 4.75) equal to 6.046693311 and -6.046693311.

Subproblem 1
x + 4.75 = 6.046693311

Simplifying
x + 4.75 = 6.046693311

Reorder the terms:
4.75 + x = 6.046693311

Solving
4.75 + x = 6.046693311

Solving for variable 'x'.

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

Add '-4.75' to each side of the equation.
4.75 + -4.75 + x = 6.046693311 + -4.75

Combine like terms: 4.75 + -4.75 = 0.00
0.00 + x = 6.046693311 + -4.75
x = 6.046693311 + -4.75

Combine like terms: 6.046693311 + -4.75 = 1.296693311
x = 1.296693311

Simplifying
x = 1.296693311

Subproblem 2
x + 4.75 = -6.046693311

Simplifying
x + 4.75 = -6.046693311

Reorder the terms:
4.75 + x = -6.046693311

Solving
4.75 + x = -6.046693311

Solving for variable 'x'.

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

Add '-4.75' to each side of the equation.
4.75 + -4.75 + x = -6.046693311 + -4.75

Combine like terms: 4.75 + -4.75 = 0.00
0.00 + x = -6.046693311 + -4.75
x = -6.046693311 + -4.75

Combine like terms: -6.046693311 + -4.75 = -10.796693311
x = -10.796693311

Simplifying
x = -10.796693311

Solution
The solution to the problem is based on the solutions
from the subproblems.
x = {1.296693311, -10.796693311}