20-5x-(x^2+8x-16)+7=

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Solution for 20-5x-(x^2+8x-16)+7= equation:


Simplifying
20 + -5x + -1(x2 + 8x + -16) + 7 = 0

Reorder the terms:
20 + -5x + -1(-16 + 8x + x2) + 7 = 0
20 + -5x + (-16 * -1 + 8x * -1 + x2 * -1) + 7 = 0
20 + -5x + (16 + -8x + -1x2) + 7 = 0

Reorder the terms:
20 + 16 + 7 + -5x + -8x + -1x2 = 0

Combine like terms: 20 + 16 = 36
36 + 7 + -5x + -8x + -1x2 = 0

Combine like terms: 36 + 7 = 43
43 + -5x + -8x + -1x2 = 0

Combine like terms: -5x + -8x = -13x
43 + -13x + -1x2 = 0

Solving
43 + -13x + -1x2 = 0

Solving for variable 'x'.

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

Divide each side by '-1'.
-43 + 13x + x2 = 0

Move the constant term to the right:

Add '43' to each side of the equation.
-43 + 13x + 43 + x2 = 0 + 43

Reorder the terms:
-43 + 43 + 13x + x2 = 0 + 43

Combine like terms: -43 + 43 = 0
0 + 13x + x2 = 0 + 43
13x + x2 = 0 + 43

Combine like terms: 0 + 43 = 43
13x + x2 = 43

The x term is 13x.  Take half its coefficient (6.5).
Square it (42.25) and add it to both sides.

Add '42.25' to each side of the equation.
13x + 42.25 + x2 = 43 + 42.25

Reorder the terms:
42.25 + 13x + x2 = 43 + 42.25

Combine like terms: 43 + 42.25 = 85.25
42.25 + 13x + x2 = 85.25

Factor a perfect square on the left side:
(x + 6.5)(x + 6.5) = 85.25

Calculate the square root of the right side: 9.233092656

Break this problem into two subproblems by setting 
(x + 6.5) equal to 9.233092656 and -9.233092656.

Subproblem 1

x + 6.5 = 9.233092656 Simplifying x + 6.5 = 9.233092656 Reorder the terms: 6.5 + x = 9.233092656 Solving 6.5 + x = 9.233092656 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-6.5' to each side of the equation. 6.5 + -6.5 + x = 9.233092656 + -6.5 Combine like terms: 6.5 + -6.5 = 0.0 0.0 + x = 9.233092656 + -6.5 x = 9.233092656 + -6.5 Combine like terms: 9.233092656 + -6.5 = 2.733092656 x = 2.733092656 Simplifying x = 2.733092656

Subproblem 2

x + 6.5 = -9.233092656 Simplifying x + 6.5 = -9.233092656 Reorder the terms: 6.5 + x = -9.233092656 Solving 6.5 + x = -9.233092656 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-6.5' to each side of the equation. 6.5 + -6.5 + x = -9.233092656 + -6.5 Combine like terms: 6.5 + -6.5 = 0.0 0.0 + x = -9.233092656 + -6.5 x = -9.233092656 + -6.5 Combine like terms: -9.233092656 + -6.5 = -15.733092656 x = -15.733092656 Simplifying x = -15.733092656

Solution

The solution to the problem is based on the solutions from the subproblems. x = {2.733092656, -15.733092656}

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