-x^2+8x=-39

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Solution for -x^2+8x=-39 equation:


Simplifying
-1x2 + 8x = -39

Reorder the terms:
8x + -1x2 = -39

Solving
8x + -1x2 = -39

Solving for variable 'x'.

Reorder the terms:
39 + 8x + -1x2 = -39 + 39

Combine like terms: -39 + 39 = 0
39 + 8x + -1x2 = 0

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

Divide each side by '-1'.
-39 + -8x + x2 = 0

Move the constant term to the right:

Add '39' to each side of the equation.
-39 + -8x + 39 + x2 = 0 + 39

Reorder the terms:
-39 + 39 + -8x + x2 = 0 + 39

Combine like terms: -39 + 39 = 0
0 + -8x + x2 = 0 + 39
-8x + x2 = 0 + 39

Combine like terms: 0 + 39 = 39
-8x + x2 = 39

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 = 39 + 16

Reorder the terms:
16 + -8x + x2 = 39 + 16

Combine like terms: 39 + 16 = 55
16 + -8x + x2 = 55

Factor a perfect square on the left side:
(x + -4)(x + -4) = 55

Calculate the square root of the right side: 7.416198487

Break this problem into two subproblems by setting 
(x + -4) equal to 7.416198487 and -7.416198487.

Subproblem 1

x + -4 = 7.416198487 Simplifying x + -4 = 7.416198487 Reorder the terms: -4 + x = 7.416198487 Solving -4 + x = 7.416198487 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 = 7.416198487 + 4 Combine like terms: -4 + 4 = 0 0 + x = 7.416198487 + 4 x = 7.416198487 + 4 Combine like terms: 7.416198487 + 4 = 11.416198487 x = 11.416198487 Simplifying x = 11.416198487

Subproblem 2

x + -4 = -7.416198487 Simplifying x + -4 = -7.416198487 Reorder the terms: -4 + x = -7.416198487 Solving -4 + x = -7.416198487 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 = -7.416198487 + 4 Combine like terms: -4 + 4 = 0 0 + x = -7.416198487 + 4 x = -7.416198487 + 4 Combine like terms: -7.416198487 + 4 = -3.416198487 x = -3.416198487 Simplifying x = -3.416198487

Solution

The solution to the problem is based on the solutions from the subproblems. x = {11.416198487, -3.416198487}

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