x^2-20x-15=0

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Solution for x^2-20x-15=0 equation:


Simplifying
x2 + -20x + -15 = 0

Reorder the terms:
-15 + -20x + x2 = 0

Solving
-15 + -20x + x2 = 0

Solving for variable 'x'.

Begin completing the square.

Move the constant term to the right:

Add '15' to each side of the equation.
-15 + -20x + 15 + x2 = 0 + 15

Reorder the terms:
-15 + 15 + -20x + x2 = 0 + 15

Combine like terms: -15 + 15 = 0
0 + -20x + x2 = 0 + 15
-20x + x2 = 0 + 15

Combine like terms: 0 + 15 = 15
-20x + x2 = 15

The x term is -20x.  Take half its coefficient (-10).
Square it (100) and add it to both sides.

Add '100' to each side of the equation.
-20x + 100 + x2 = 15 + 100

Reorder the terms:
100 + -20x + x2 = 15 + 100

Combine like terms: 15 + 100 = 115
100 + -20x + x2 = 115

Factor a perfect square on the left side:
(x + -10)(x + -10) = 115

Calculate the square root of the right side: 10.723805295

Break this problem into two subproblems by setting 
(x + -10) equal to 10.723805295 and -10.723805295.

Subproblem 1

x + -10 = 10.723805295 Simplifying x + -10 = 10.723805295 Reorder the terms: -10 + x = 10.723805295 Solving -10 + x = 10.723805295 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '10' to each side of the equation. -10 + 10 + x = 10.723805295 + 10 Combine like terms: -10 + 10 = 0 0 + x = 10.723805295 + 10 x = 10.723805295 + 10 Combine like terms: 10.723805295 + 10 = 20.723805295 x = 20.723805295 Simplifying x = 20.723805295

Subproblem 2

x + -10 = -10.723805295 Simplifying x + -10 = -10.723805295 Reorder the terms: -10 + x = -10.723805295 Solving -10 + x = -10.723805295 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '10' to each side of the equation. -10 + 10 + x = -10.723805295 + 10 Combine like terms: -10 + 10 = 0 0 + x = -10.723805295 + 10 x = -10.723805295 + 10 Combine like terms: -10.723805295 + 10 = -0.723805295 x = -0.723805295 Simplifying x = -0.723805295

Solution

The solution to the problem is based on the solutions from the subproblems. x = {20.723805295, -0.723805295}

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