320=(x+2)(2x+4)

Solution for 320=(x+2)(2x+4) equation:

Simplifying
320 = (x + 2)(2x + 4)

Reorder the terms:
320 = (2 + x)(2x + 4)

Reorder the terms:
320 = (2 + x)(4 + 2x)

Multiply (2 + x) * (4 + 2x)
320 = (2(4 + 2x) + x(4 + 2x))
320 = ((4 * 2 + 2x * 2) + x(4 + 2x))
320 = ((8 + 4x) + x(4 + 2x))
320 = (8 + 4x + (4 * x + 2x * x))
320 = (8 + 4x + (4x + 2x2))

Combine like terms: 4x + 4x = 8x
320 = (8 + 8x + 2x2)

Solving
320 = 8 + 8x + 2x2

Solving for variable 'x'.

Combine like terms: 320 + -8 = 312
312 + -8x + -2x2 = 8 + 8x + 2x2 + -8 + -8x + -2x2

Reorder the terms:
312 + -8x + -2x2 = 8 + -8 + 8x + -8x + 2x2 + -2x2

Combine like terms: 8 + -8 = 0
312 + -8x + -2x2 = 0 + 8x + -8x + 2x2 + -2x2
312 + -8x + -2x2 = 8x + -8x + 2x2 + -2x2

Combine like terms: 8x + -8x = 0
312 + -8x + -2x2 = 0 + 2x2 + -2x2
312 + -8x + -2x2 = 2x2 + -2x2

Combine like terms: 2x2 + -2x2 = 0
312 + -8x + -2x2 = 0

Factor out the Greatest Common Factor (GCF), '2'.
2(156 + -4x + -1x2) = 0

Ignore the factor 2.
Subproblem 1
Set the factor '(156 + -4x + -1x2)' equal to zero and attempt to solve:

Simplifying
156 + -4x + -1x2 = 0

Solving
156 + -4x + -1x2 = 0

Begin completing the square.  Divide all terms by
-1 the coefficient of the squared term: 

Divide each side by '-1'.
-156 + 4x + x2 = 0

Move the constant term to the right:

Add '156' to each side of the equation.
-156 + 4x + 156 + x2 = 0 + 156

Reorder the terms:
-156 + 156 + 4x + x2 = 0 + 156

Combine like terms: -156 + 156 = 0
0 + 4x + x2 = 0 + 156
4x + x2 = 0 + 156

Combine like terms: 0 + 156 = 156
4x + x2 = 156

The x term is 4x.  Take half its coefficient (2).
Square it (4) and add it to both sides.

Add '4' to each side of the equation.
4x + 4 + x2 = 156 + 4

Reorder the terms:
4 + 4x + x2 = 156 + 4

Combine like terms: 156 + 4 = 160
4 + 4x + x2 = 160

Factor a perfect square on the left side:
(x + 2)(x + 2) = 160

Calculate the square root of the right side: 12.649110641

Break this problem into two subproblems by setting 
(x + 2) equal to 12.649110641 and -12.649110641.

Subproblem 1
x + 2 = 12.649110641

Simplifying
x + 2 = 12.649110641

Reorder the terms:
2 + x = 12.649110641

Solving
2 + x = 12.649110641

Solving for variable 'x'.

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

Add '-2' to each side of the equation.
2 + -2 + x = 12.649110641 + -2

Combine like terms: 2 + -2 = 0
0 + x = 12.649110641 + -2
x = 12.649110641 + -2

Combine like terms: 12.649110641 + -2 = 10.649110641
x = 10.649110641

Simplifying
x = 10.649110641

Subproblem 2
x + 2 = -12.649110641

Simplifying
x + 2 = -12.649110641

Reorder the terms:
2 + x = -12.649110641

Solving
2 + x = -12.649110641

Solving for variable 'x'.

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

Add '-2' to each side of the equation.
2 + -2 + x = -12.649110641 + -2

Combine like terms: 2 + -2 = 0
0 + x = -12.649110641 + -2
x = -12.649110641 + -2

Combine like terms: -12.649110641 + -2 = -14.649110641
x = -14.649110641

Simplifying
x = -14.649110641

Solution
The solution to the problem is based on the solutions
from the subproblems.
x = {10.649110641, -14.649110641}
Solution
x = {10.649110641, -14.649110641}