x^2-4x-121=0

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Solution for x^2-4x-121=0 equation:


Simplifying
x2 + -4x + -121 = 0

Reorder the terms:
-121 + -4x + x2 = 0

Solving
-121 + -4x + x2 = 0

Solving for variable 'x'.

Begin completing the square.

Move the constant term to the right:

Add '121' to each side of the equation.
-121 + -4x + 121 + x2 = 0 + 121

Reorder the terms:
-121 + 121 + -4x + x2 = 0 + 121

Combine like terms: -121 + 121 = 0
0 + -4x + x2 = 0 + 121
-4x + x2 = 0 + 121

Combine like terms: 0 + 121 = 121
-4x + x2 = 121

The x term is -4x.  Take half its coefficient (-2).
Square it (4) and add it to both sides.

Add '4' to each side of the equation.
-4x + 4 + x2 = 121 + 4

Reorder the terms:
4 + -4x + x2 = 121 + 4

Combine like terms: 121 + 4 = 125
4 + -4x + x2 = 125

Factor a perfect square on the left side:
(x + -2)(x + -2) = 125

Calculate the square root of the right side: 11.180339887

Break this problem into two subproblems by setting 
(x + -2) equal to 11.180339887 and -11.180339887.

Subproblem 1

x + -2 = 11.180339887 Simplifying x + -2 = 11.180339887 Reorder the terms: -2 + x = 11.180339887 Solving -2 + x = 11.180339887 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '2' to each side of the equation. -2 + 2 + x = 11.180339887 + 2 Combine like terms: -2 + 2 = 0 0 + x = 11.180339887 + 2 x = 11.180339887 + 2 Combine like terms: 11.180339887 + 2 = 13.180339887 x = 13.180339887 Simplifying x = 13.180339887

Subproblem 2

x + -2 = -11.180339887 Simplifying x + -2 = -11.180339887 Reorder the terms: -2 + x = -11.180339887 Solving -2 + x = -11.180339887 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '2' to each side of the equation. -2 + 2 + x = -11.180339887 + 2 Combine like terms: -2 + 2 = 0 0 + x = -11.180339887 + 2 x = -11.180339887 + 2 Combine like terms: -11.180339887 + 2 = -9.180339887 x = -9.180339887 Simplifying x = -9.180339887

Solution

The solution to the problem is based on the solutions from the subproblems. x = {13.180339887, -9.180339887}

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