x^2-18x-8=0

Solution for x^2-18x-8=0 equation:

Simplifying
x2 + -18x + -8 = 0

Reorder the terms:
-8 + -18x + x2 = 0

Solving
-8 + -18x + x2 = 0

Solving for variable 'x'.

Begin completing the square.

Move the constant term to the right:

Add '8' to each side of the equation.
-8 + -18x + 8 + x2 = 0 + 8

Reorder the terms:
-8 + 8 + -18x + x2 = 0 + 8

Combine like terms: -8 + 8 = 0
0 + -18x + x2 = 0 + 8
-18x + x2 = 0 + 8

Combine like terms: 0 + 8 = 8
-18x + x2 = 8

The x term is -18x.  Take half its coefficient (-9).
Square it (81) and add it to both sides.

Add '81' to each side of the equation.
-18x + 81 + x2 = 8 + 81

Reorder the terms:
81 + -18x + x2 = 8 + 81

Combine like terms: 8 + 81 = 89
81 + -18x + x2 = 89

Factor a perfect square on the left side:
(x + -9)(x + -9) = 89

Calculate the square root of the right side: 9.433981132

Break this problem into two subproblems by setting 
(x + -9) equal to 9.433981132 and -9.433981132.

Subproblem 1
x + -9 = 9.433981132

Simplifying
x + -9 = 9.433981132

Reorder the terms:
-9 + x = 9.433981132

Solving
-9 + x = 9.433981132

Solving for variable 'x'.

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

Add '9' to each side of the equation.
-9 + 9 + x = 9.433981132 + 9

Combine like terms: -9 + 9 = 0
0 + x = 9.433981132 + 9
x = 9.433981132 + 9

Combine like terms: 9.433981132 + 9 = 18.433981132
x = 18.433981132

Simplifying
x = 18.433981132

Subproblem 2
x + -9 = -9.433981132

Simplifying
x + -9 = -9.433981132

Reorder the terms:
-9 + x = -9.433981132

Solving
-9 + x = -9.433981132

Solving for variable 'x'.

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

Add '9' to each side of the equation.
-9 + 9 + x = -9.433981132 + 9

Combine like terms: -9 + 9 = 0
0 + x = -9.433981132 + 9
x = -9.433981132 + 9

Combine like terms: -9.433981132 + 9 = -0.433981132
x = -0.433981132

Simplifying
x = -0.433981132

Solution
The solution to the problem is based on the solutions
from the subproblems.
x = {18.433981132, -0.433981132}