(2x+8)(2x+7)=58

Solution for (2x+8)(2x+7)=58 equation:

Simplifying
(2x + 8)(2x + 7) = 58

Reorder the terms:
(8 + 2x)(2x + 7) = 58

Reorder the terms:
(8 + 2x)(7 + 2x) = 58

Multiply (8 + 2x) * (7 + 2x)
(8(7 + 2x) + 2x * (7 + 2x)) = 58
((7 * 8 + 2x * 8) + 2x * (7 + 2x)) = 58
((56 + 16x) + 2x * (7 + 2x)) = 58
(56 + 16x + (7 * 2x + 2x * 2x)) = 58
(56 + 16x + (14x + 4x2)) = 58

Combine like terms: 16x + 14x = 30x
(56 + 30x + 4x2) = 58

Solving
56 + 30x + 4x2 = 58

Solving for variable 'x'.

Reorder the terms:
56 + -58 + 30x + 4x2 = 58 + -58

Combine like terms: 56 + -58 = -2
-2 + 30x + 4x2 = 58 + -58

Combine like terms: 58 + -58 = 0
-2 + 30x + 4x2 = 0

Factor out the Greatest Common Factor (GCF), '2'.
2(-1 + 15x + 2x2) = 0

Ignore the factor 2.
Subproblem 1
Set the factor '(-1 + 15x + 2x2)' equal to zero and attempt to solve:

Simplifying
-1 + 15x + 2x2 = 0

Solving
-1 + 15x + 2x2 = 0

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

Divide each side by '2'.
-0.5 + 7.5x + x2 = 0

Move the constant term to the right:

Add '0.5' to each side of the equation.
-0.5 + 7.5x + 0.5 + x2 = 0 + 0.5

Reorder the terms:
-0.5 + 0.5 + 7.5x + x2 = 0 + 0.5

Combine like terms: -0.5 + 0.5 = 0.0
0.0 + 7.5x + x2 = 0 + 0.5
7.5x + x2 = 0 + 0.5

Combine like terms: 0 + 0.5 = 0.5
7.5x + x2 = 0.5

The x term is 7.5x.  Take half its coefficient (3.75).
Square it (14.0625) and add it to both sides.

Add '14.0625' to each side of the equation.
7.5x + 14.0625 + x2 = 0.5 + 14.0625

Reorder the terms:
14.0625 + 7.5x + x2 = 0.5 + 14.0625

Combine like terms: 0.5 + 14.0625 = 14.5625
14.0625 + 7.5x + x2 = 14.5625

Factor a perfect square on the left side:
(x + 3.75)(x + 3.75) = 14.5625

Calculate the square root of the right side: 3.816084381

Break this problem into two subproblems by setting 
(x + 3.75) equal to 3.816084381 and -3.816084381.

Subproblem 1
x + 3.75 = 3.816084381

Simplifying
x + 3.75 = 3.816084381

Reorder the terms:
3.75 + x = 3.816084381

Solving
3.75 + x = 3.816084381

Solving for variable 'x'.

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

Add '-3.75' to each side of the equation.
3.75 + -3.75 + x = 3.816084381 + -3.75

Combine like terms: 3.75 + -3.75 = 0.00
0.00 + x = 3.816084381 + -3.75
x = 3.816084381 + -3.75

Combine like terms: 3.816084381 + -3.75 = 0.066084381
x = 0.066084381

Simplifying
x = 0.066084381

Subproblem 2
x + 3.75 = -3.816084381

Simplifying
x + 3.75 = -3.816084381

Reorder the terms:
3.75 + x = -3.816084381

Solving
3.75 + x = -3.816084381

Solving for variable 'x'.

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

Add '-3.75' to each side of the equation.
3.75 + -3.75 + x = -3.816084381 + -3.75

Combine like terms: 3.75 + -3.75 = 0.00
0.00 + x = -3.816084381 + -3.75
x = -3.816084381 + -3.75

Combine like terms: -3.816084381 + -3.75 = -7.566084381
x = -7.566084381

Simplifying
x = -7.566084381

Solution
The solution to the problem is based on the solutions
from the subproblems.
x = {0.066084381, -7.566084381}
Solution
x = {0.066084381, -7.566084381}