x^2+8x+16=98.6

Solution for x^2+8x+16=98.6 equation:

Simplifying
x2 + 8x + 16 = 98.6

Reorder the terms:
16 + 8x + x2 = 98.6

Solving
16 + 8x + x2 = 98.6

Solving for variable 'x'.

Reorder the terms:
16 + -98.6 + 8x + x2 = 98.6 + -98.6

Combine like terms: 16 + -98.6 = -82.6
-82.6 + 8x + x2 = 98.6 + -98.6

Combine like terms: 98.6 + -98.6 = 0.0
-82.6 + 8x + x2 = 0.0

Begin completing the square.

Move the constant term to the right:

Add '82.6' to each side of the equation.
-82.6 + 8x + 82.6 + x2 = 0.0 + 82.6

Reorder the terms:
-82.6 + 82.6 + 8x + x2 = 0.0 + 82.6

Combine like terms: -82.6 + 82.6 = 0.0
0.0 + 8x + x2 = 0.0 + 82.6
8x + x2 = 0.0 + 82.6

Combine like terms: 0.0 + 82.6 = 82.6
8x + x2 = 82.6

The x term is 8x.  Take half its coefficient (4).
Square it (16) and add it to both sides.

Add '16' to each side of the equation.
8x + 16 + x2 = 82.6 + 16

Reorder the terms:
16 + 8x + x2 = 82.6 + 16

Combine like terms: 82.6 + 16 = 98.6
16 + 8x + x2 = 98.6

Factor a perfect square on the left side:
(x + 4)(x + 4) = 98.6

Calculate the square root of the right side: 9.92975327

Break this problem into two subproblems by setting 
(x + 4) equal to 9.92975327 and -9.92975327.

Subproblem 1
x + 4 = 9.92975327

Simplifying
x + 4 = 9.92975327

Reorder the terms:
4 + x = 9.92975327

Solving
4 + x = 9.92975327

Solving for variable 'x'.

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

Add '-4' to each side of the equation.
4 + -4 + x = 9.92975327 + -4

Combine like terms: 4 + -4 = 0
0 + x = 9.92975327 + -4
x = 9.92975327 + -4

Combine like terms: 9.92975327 + -4 = 5.92975327
x = 5.92975327

Simplifying
x = 5.92975327

Subproblem 2
x + 4 = -9.92975327

Simplifying
x + 4 = -9.92975327

Reorder the terms:
4 + x = -9.92975327

Solving
4 + x = -9.92975327

Solving for variable 'x'.

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

Add '-4' to each side of the equation.
4 + -4 + x = -9.92975327 + -4

Combine like terms: 4 + -4 = 0
0 + x = -9.92975327 + -4
x = -9.92975327 + -4

Combine like terms: -9.92975327 + -4 = -13.92975327
x = -13.92975327

Simplifying
x = -13.92975327

Solution
The solution to the problem is based on the solutions
from the subproblems.
x = {5.92975327, -13.92975327}