x^2-9x-72=

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Solution for x^2-9x-72= equation:


Simplifying
x2 + -9x + -72 = 0

Reorder the terms:
-72 + -9x + x2 = 0

Solving
-72 + -9x + x2 = 0

Solving for variable 'x'.

Begin completing the square.

Move the constant term to the right:

Add '72' to each side of the equation.
-72 + -9x + 72 + x2 = 0 + 72

Reorder the terms:
-72 + 72 + -9x + x2 = 0 + 72

Combine like terms: -72 + 72 = 0
0 + -9x + x2 = 0 + 72
-9x + x2 = 0 + 72

Combine like terms: 0 + 72 = 72
-9x + x2 = 72

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 = 72 + 20.25

Reorder the terms:
20.25 + -9x + x2 = 72 + 20.25

Combine like terms: 72 + 20.25 = 92.25
20.25 + -9x + x2 = 92.25

Factor a perfect square on the left side:
(x + -4.5)(x + -4.5) = 92.25

Calculate the square root of the right side: 9.604686356

Break this problem into two subproblems by setting 
(x + -4.5) equal to 9.604686356 and -9.604686356.

Subproblem 1

x + -4.5 = 9.604686356 Simplifying x + -4.5 = 9.604686356 Reorder the terms: -4.5 + x = 9.604686356 Solving -4.5 + x = 9.604686356 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 = 9.604686356 + 4.5 Combine like terms: -4.5 + 4.5 = 0.0 0.0 + x = 9.604686356 + 4.5 x = 9.604686356 + 4.5 Combine like terms: 9.604686356 + 4.5 = 14.104686356 x = 14.104686356 Simplifying x = 14.104686356

Subproblem 2

x + -4.5 = -9.604686356 Simplifying x + -4.5 = -9.604686356 Reorder the terms: -4.5 + x = -9.604686356 Solving -4.5 + x = -9.604686356 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 = -9.604686356 + 4.5 Combine like terms: -4.5 + 4.5 = 0.0 0.0 + x = -9.604686356 + 4.5 x = -9.604686356 + 4.5 Combine like terms: -9.604686356 + 4.5 = -5.104686356 x = -5.104686356 Simplifying x = -5.104686356

Solution

The solution to the problem is based on the solutions from the subproblems. x = {14.104686356, -5.104686356}

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