x^2-x-16=0

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Solution for x^2-x-16=0 equation:


Simplifying
x2 + -1x + -16 = 0

Reorder the terms:
-16 + -1x + x2 = 0

Solving
-16 + -1x + x2 = 0

Solving for variable 'x'.

Begin completing the square.

Move the constant term to the right:

Add '16' to each side of the equation.
-16 + -1x + 16 + x2 = 0 + 16

Reorder the terms:
-16 + 16 + -1x + x2 = 0 + 16

Combine like terms: -16 + 16 = 0
0 + -1x + x2 = 0 + 16
-1x + x2 = 0 + 16

Combine like terms: 0 + 16 = 16
-1x + x2 = 16

The x term is -1x.  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.
-1x + 0.25 + x2 = 16 + 0.25

Reorder the terms:
0.25 + -1x + x2 = 16 + 0.25

Combine like terms: 16 + 0.25 = 16.25
0.25 + -1x + x2 = 16.25

Factor a perfect square on the left side:
(x + -0.5)(x + -0.5) = 16.25

Calculate the square root of the right side: 4.031128874

Break this problem into two subproblems by setting 
(x + -0.5) equal to 4.031128874 and -4.031128874.

Subproblem 1

x + -0.5 = 4.031128874 Simplifying x + -0.5 = 4.031128874 Reorder the terms: -0.5 + x = 4.031128874 Solving -0.5 + x = 4.031128874 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 = 4.031128874 + 0.5 Combine like terms: -0.5 + 0.5 = 0.0 0.0 + x = 4.031128874 + 0.5 x = 4.031128874 + 0.5 Combine like terms: 4.031128874 + 0.5 = 4.531128874 x = 4.531128874 Simplifying x = 4.531128874

Subproblem 2

x + -0.5 = -4.031128874 Simplifying x + -0.5 = -4.031128874 Reorder the terms: -0.5 + x = -4.031128874 Solving -0.5 + x = -4.031128874 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 = -4.031128874 + 0.5 Combine like terms: -0.5 + 0.5 = 0.0 0.0 + x = -4.031128874 + 0.5 x = -4.031128874 + 0.5 Combine like terms: -4.031128874 + 0.5 = -3.531128874 x = -3.531128874 Simplifying x = -3.531128874

Solution

The solution to the problem is based on the solutions from the subproblems. x = {4.531128874, -3.531128874}

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