0=x^2-8x-87

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Solution for 0=x^2-8x-87 equation:


Simplifying
0 = x2 + -8x + -87

Reorder the terms:
0 = -87 + -8x + x2

Solving
0 = -87 + -8x + x2

Solving for variable 'x'.

Combine like terms: 0 + 87 = 87
87 + 8x + -1x2 = -87 + -8x + x2 + 87 + 8x + -1x2

Reorder the terms:
87 + 8x + -1x2 = -87 + 87 + -8x + 8x + x2 + -1x2

Combine like terms: -87 + 87 = 0
87 + 8x + -1x2 = 0 + -8x + 8x + x2 + -1x2
87 + 8x + -1x2 = -8x + 8x + x2 + -1x2

Combine like terms: -8x + 8x = 0
87 + 8x + -1x2 = 0 + x2 + -1x2
87 + 8x + -1x2 = x2 + -1x2

Combine like terms: x2 + -1x2 = 0
87 + 8x + -1x2 = 0

Begin completing the square.  Divide all terms by
-1 the coefficient of the squared term: 

Divide each side by '-1'.
-87 + -8x + x2 = 0

Move the constant term to the right:

Add '87' to each side of the equation.
-87 + -8x + 87 + x2 = 0 + 87

Reorder the terms:
-87 + 87 + -8x + x2 = 0 + 87

Combine like terms: -87 + 87 = 0
0 + -8x + x2 = 0 + 87
-8x + x2 = 0 + 87

Combine like terms: 0 + 87 = 87
-8x + x2 = 87

The x term is -8x.  Take half its coefficient (-4).
Square it (16) and add it to both sides.

Add '16' to each side of the equation.
-8x + 16 + x2 = 87 + 16

Reorder the terms:
16 + -8x + x2 = 87 + 16

Combine like terms: 87 + 16 = 103
16 + -8x + x2 = 103

Factor a perfect square on the left side:
(x + -4)(x + -4) = 103

Calculate the square root of the right side: 10.148891565

Break this problem into two subproblems by setting 
(x + -4) equal to 10.148891565 and -10.148891565.

Subproblem 1

x + -4 = 10.148891565 Simplifying x + -4 = 10.148891565 Reorder the terms: -4 + x = 10.148891565 Solving -4 + x = 10.148891565 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '4' to each side of the equation. -4 + 4 + x = 10.148891565 + 4 Combine like terms: -4 + 4 = 0 0 + x = 10.148891565 + 4 x = 10.148891565 + 4 Combine like terms: 10.148891565 + 4 = 14.148891565 x = 14.148891565 Simplifying x = 14.148891565

Subproblem 2

x + -4 = -10.148891565 Simplifying x + -4 = -10.148891565 Reorder the terms: -4 + x = -10.148891565 Solving -4 + x = -10.148891565 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '4' to each side of the equation. -4 + 4 + x = -10.148891565 + 4 Combine like terms: -4 + 4 = 0 0 + x = -10.148891565 + 4 x = -10.148891565 + 4 Combine like terms: -10.148891565 + 4 = -6.148891565 x = -6.148891565 Simplifying x = -6.148891565

Solution

The solution to the problem is based on the solutions from the subproblems. x = {14.148891565, -6.148891565}

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