2x^2-13x-21=(x-5)2

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Solution for 2x^2-13x-21=(x-5)2 equation:


Simplifying
2x2 + -13x + -21 = (x + -5) * 2

Reorder the terms:
-21 + -13x + 2x2 = (x + -5) * 2

Reorder the terms:
-21 + -13x + 2x2 = (-5 + x) * 2

Reorder the terms for easier multiplication:
-21 + -13x + 2x2 = 2(-5 + x)
-21 + -13x + 2x2 = (-5 * 2 + x * 2)
-21 + -13x + 2x2 = (-10 + 2x)

Solving
-21 + -13x + 2x2 = -10 + 2x

Solving for variable 'x'.

Reorder the terms:
-21 + 10 + -13x + -2x + 2x2 = -10 + 2x + 10 + -2x

Combine like terms: -21 + 10 = -11
-11 + -13x + -2x + 2x2 = -10 + 2x + 10 + -2x

Combine like terms: -13x + -2x = -15x
-11 + -15x + 2x2 = -10 + 2x + 10 + -2x

Reorder the terms:
-11 + -15x + 2x2 = -10 + 10 + 2x + -2x

Combine like terms: -10 + 10 = 0
-11 + -15x + 2x2 = 0 + 2x + -2x
-11 + -15x + 2x2 = 2x + -2x

Combine like terms: 2x + -2x = 0
-11 + -15x + 2x2 = 0

Begin completing the square.  Divide all terms by
2 the coefficient of the squared term: 

Divide each side by '2'.
-5.5 + -7.5x + x2 = 0

Move the constant term to the right:

Add '5.5' to each side of the equation.
-5.5 + -7.5x + 5.5 + x2 = 0 + 5.5

Reorder the terms:
-5.5 + 5.5 + -7.5x + x2 = 0 + 5.5

Combine like terms: -5.5 + 5.5 = 0.0
0.0 + -7.5x + x2 = 0 + 5.5
-7.5x + x2 = 0 + 5.5

Combine like terms: 0 + 5.5 = 5.5
-7.5x + x2 = 5.5

The x term is -7.5x.  Take half its coefficient (-3.75).
Square it (14.0625) and add it to both sides.

Add '14.0625' to each side of the equation.
-7.5x + 14.0625 + x2 = 5.5 + 14.0625

Reorder the terms:
14.0625 + -7.5x + x2 = 5.5 + 14.0625

Combine like terms: 5.5 + 14.0625 = 19.5625
14.0625 + -7.5x + x2 = 19.5625

Factor a perfect square on the left side:
(x + -3.75)(x + -3.75) = 19.5625

Calculate the square root of the right side: 4.422951503

Break this problem into two subproblems by setting 
(x + -3.75) equal to 4.422951503 and -4.422951503.

Subproblem 1

x + -3.75 = 4.422951503 Simplifying x + -3.75 = 4.422951503 Reorder the terms: -3.75 + x = 4.422951503 Solving -3.75 + x = 4.422951503 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '3.75' to each side of the equation. -3.75 + 3.75 + x = 4.422951503 + 3.75 Combine like terms: -3.75 + 3.75 = 0.00 0.00 + x = 4.422951503 + 3.75 x = 4.422951503 + 3.75 Combine like terms: 4.422951503 + 3.75 = 8.172951503 x = 8.172951503 Simplifying x = 8.172951503

Subproblem 2

x + -3.75 = -4.422951503 Simplifying x + -3.75 = -4.422951503 Reorder the terms: -3.75 + x = -4.422951503 Solving -3.75 + x = -4.422951503 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '3.75' to each side of the equation. -3.75 + 3.75 + x = -4.422951503 + 3.75 Combine like terms: -3.75 + 3.75 = 0.00 0.00 + x = -4.422951503 + 3.75 x = -4.422951503 + 3.75 Combine like terms: -4.422951503 + 3.75 = -0.672951503 x = -0.672951503 Simplifying x = -0.672951503

Solution

The solution to the problem is based on the solutions from the subproblems. x = {8.172951503, -0.672951503}

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