x^2+18x-90=0

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Solution for x^2+18x-90=0 equation:


Simplifying
x2 + 18x + -90 = 0

Reorder the terms:
-90 + 18x + x2 = 0

Solving
-90 + 18x + x2 = 0

Solving for variable 'x'.

Begin completing the square.

Move the constant term to the right:

Add '90' to each side of the equation.
-90 + 18x + 90 + x2 = 0 + 90

Reorder the terms:
-90 + 90 + 18x + x2 = 0 + 90

Combine like terms: -90 + 90 = 0
0 + 18x + x2 = 0 + 90
18x + x2 = 0 + 90

Combine like terms: 0 + 90 = 90
18x + x2 = 90

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 = 90 + 81

Reorder the terms:
81 + 18x + x2 = 90 + 81

Combine like terms: 90 + 81 = 171
81 + 18x + x2 = 171

Factor a perfect square on the left side:
(x + 9)(x + 9) = 171

Calculate the square root of the right side: 13.076696831

Break this problem into two subproblems by setting 
(x + 9) equal to 13.076696831 and -13.076696831.

Subproblem 1

x + 9 = 13.076696831 Simplifying x + 9 = 13.076696831 Reorder the terms: 9 + x = 13.076696831 Solving 9 + x = 13.076696831 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 = 13.076696831 + -9 Combine like terms: 9 + -9 = 0 0 + x = 13.076696831 + -9 x = 13.076696831 + -9 Combine like terms: 13.076696831 + -9 = 4.076696831 x = 4.076696831 Simplifying x = 4.076696831

Subproblem 2

x + 9 = -13.076696831 Simplifying x + 9 = -13.076696831 Reorder the terms: 9 + x = -13.076696831 Solving 9 + x = -13.076696831 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 = -13.076696831 + -9 Combine like terms: 9 + -9 = 0 0 + x = -13.076696831 + -9 x = -13.076696831 + -9 Combine like terms: -13.076696831 + -9 = -22.076696831 x = -22.076696831 Simplifying x = -22.076696831

Solution

The solution to the problem is based on the solutions from the subproblems. x = {4.076696831, -22.076696831}

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