2x(-9-x)=-13

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Solution for 2x(-9-x)=-13 equation:


Simplifying
2x(-9 + -1x) = -13
(-9 * 2x + -1x * 2x) = -13
(-18x + -2x2) = -13

Solving
-18x + -2x2 = -13

Solving for variable 'x'.

Reorder the terms:
13 + -18x + -2x2 = -13 + 13

Combine like terms: -13 + 13 = 0
13 + -18x + -2x2 = 0

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

Divide each side by '-2'.
-6.5 + 9x + x2 = 0

Move the constant term to the right:

Add '6.5' to each side of the equation.
-6.5 + 9x + 6.5 + x2 = 0 + 6.5

Reorder the terms:
-6.5 + 6.5 + 9x + x2 = 0 + 6.5

Combine like terms: -6.5 + 6.5 = 0.0
0.0 + 9x + x2 = 0 + 6.5
9x + x2 = 0 + 6.5

Combine like terms: 0 + 6.5 = 6.5
9x + x2 = 6.5

The x term is 9x.  Take half its coefficient (4.5).
Square it (20.25) and add it to both sides.

Add '20.25' to each side of the equation.
9x + 20.25 + x2 = 6.5 + 20.25

Reorder the terms:
20.25 + 9x + x2 = 6.5 + 20.25

Combine like terms: 6.5 + 20.25 = 26.75
20.25 + 9x + x2 = 26.75

Factor a perfect square on the left side:
(x + 4.5)(x + 4.5) = 26.75

Calculate the square root of the right side: 5.172040216

Break this problem into two subproblems by setting 
(x + 4.5) equal to 5.172040216 and -5.172040216.

Subproblem 1

x + 4.5 = 5.172040216 Simplifying x + 4.5 = 5.172040216 Reorder the terms: 4.5 + x = 5.172040216 Solving 4.5 + x = 5.172040216 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-4.5' to each side of the equation. 4.5 + -4.5 + x = 5.172040216 + -4.5 Combine like terms: 4.5 + -4.5 = 0.0 0.0 + x = 5.172040216 + -4.5 x = 5.172040216 + -4.5 Combine like terms: 5.172040216 + -4.5 = 0.672040216 x = 0.672040216 Simplifying x = 0.672040216

Subproblem 2

x + 4.5 = -5.172040216 Simplifying x + 4.5 = -5.172040216 Reorder the terms: 4.5 + x = -5.172040216 Solving 4.5 + x = -5.172040216 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-4.5' to each side of the equation. 4.5 + -4.5 + x = -5.172040216 + -4.5 Combine like terms: 4.5 + -4.5 = 0.0 0.0 + x = -5.172040216 + -4.5 x = -5.172040216 + -4.5 Combine like terms: -5.172040216 + -4.5 = -9.672040216 x = -9.672040216 Simplifying x = -9.672040216

Solution

The solution to the problem is based on the solutions from the subproblems. x = {0.672040216, -9.672040216}

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