x^2+x-128=0

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Solution for x^2+x-128=0 equation:


Simplifying
x2 + x + -128 = 0

Reorder the terms:
-128 + x + x2 = 0

Solving
-128 + x + x2 = 0

Solving for variable 'x'.

Begin completing the square.

Move the constant term to the right:

Add '128' to each side of the equation.
-128 + x + 128 + x2 = 0 + 128

Reorder the terms:
-128 + 128 + x + x2 = 0 + 128

Combine like terms: -128 + 128 = 0
0 + x + x2 = 0 + 128
x + x2 = 0 + 128

Combine like terms: 0 + 128 = 128
x + x2 = 128

The x term is x.  Take half its coefficient (0.5).
Square it (0.25) and add it to both sides.

Add '0.25' to each side of the equation.
x + 0.25 + x2 = 128 + 0.25

Reorder the terms:
0.25 + x + x2 = 128 + 0.25

Combine like terms: 128 + 0.25 = 128.25
0.25 + x + x2 = 128.25

Factor a perfect square on the left side:
(x + 0.5)(x + 0.5) = 128.25

Calculate the square root of the right side: 11.324751653

Break this problem into two subproblems by setting 
(x + 0.5) equal to 11.324751653 and -11.324751653.

Subproblem 1

x + 0.5 = 11.324751653 Simplifying x + 0.5 = 11.324751653 Reorder the terms: 0.5 + x = 11.324751653 Solving 0.5 + x = 11.324751653 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.5' to each side of the equation. 0.5 + -0.5 + x = 11.324751653 + -0.5 Combine like terms: 0.5 + -0.5 = 0.0 0.0 + x = 11.324751653 + -0.5 x = 11.324751653 + -0.5 Combine like terms: 11.324751653 + -0.5 = 10.824751653 x = 10.824751653 Simplifying x = 10.824751653

Subproblem 2

x + 0.5 = -11.324751653 Simplifying x + 0.5 = -11.324751653 Reorder the terms: 0.5 + x = -11.324751653 Solving 0.5 + x = -11.324751653 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.5' to each side of the equation. 0.5 + -0.5 + x = -11.324751653 + -0.5 Combine like terms: 0.5 + -0.5 = 0.0 0.0 + x = -11.324751653 + -0.5 x = -11.324751653 + -0.5 Combine like terms: -11.324751653 + -0.5 = -11.824751653 x = -11.824751653 Simplifying x = -11.824751653

Solution

The solution to the problem is based on the solutions from the subproblems. x = {10.824751653, -11.824751653}

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