x^2-8x-18=0

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


Simplifying
x2 + -8x + -18 = 0

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

Solving
-18 + -8x + x2 = 0

Solving for variable 'x'.

Begin completing the square.

Move the constant term to the right:

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

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

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

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

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 = 18 + 16

Reorder the terms:
16 + -8x + x2 = 18 + 16

Combine like terms: 18 + 16 = 34
16 + -8x + x2 = 34

Factor a perfect square on the left side:
(x + -4)(x + -4) = 34

Calculate the square root of the right side: 5.830951895

Break this problem into two subproblems by setting 
(x + -4) equal to 5.830951895 and -5.830951895.

Subproblem 1

x + -4 = 5.830951895 Simplifying x + -4 = 5.830951895 Reorder the terms: -4 + x = 5.830951895 Solving -4 + x = 5.830951895 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 = 5.830951895 + 4 Combine like terms: -4 + 4 = 0 0 + x = 5.830951895 + 4 x = 5.830951895 + 4 Combine like terms: 5.830951895 + 4 = 9.830951895 x = 9.830951895 Simplifying x = 9.830951895

Subproblem 2

x + -4 = -5.830951895 Simplifying x + -4 = -5.830951895 Reorder the terms: -4 + x = -5.830951895 Solving -4 + x = -5.830951895 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 = -5.830951895 + 4 Combine like terms: -4 + 4 = 0 0 + x = -5.830951895 + 4 x = -5.830951895 + 4 Combine like terms: -5.830951895 + 4 = -1.830951895 x = -1.830951895 Simplifying x = -1.830951895

Solution

The solution to the problem is based on the solutions from the subproblems. x = {9.830951895, -1.830951895}

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