x^2-9x-40=0

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Solution for x^2-9x-40=0 equation:


Simplifying
x2 + -9x + -40 = 0

Reorder the terms:
-40 + -9x + x2 = 0

Solving
-40 + -9x + x2 = 0

Solving for variable 'x'.

Begin completing the square.

Move the constant term to the right:

Add '40' to each side of the equation.
-40 + -9x + 40 + x2 = 0 + 40

Reorder the terms:
-40 + 40 + -9x + x2 = 0 + 40

Combine like terms: -40 + 40 = 0
0 + -9x + x2 = 0 + 40
-9x + x2 = 0 + 40

Combine like terms: 0 + 40 = 40
-9x + x2 = 40

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 = 40 + 20.25

Reorder the terms:
20.25 + -9x + x2 = 40 + 20.25

Combine like terms: 40 + 20.25 = 60.25
20.25 + -9x + x2 = 60.25

Factor a perfect square on the left side:
(x + -4.5)(x + -4.5) = 60.25

Calculate the square root of the right side: 7.762087348

Break this problem into two subproblems by setting 
(x + -4.5) equal to 7.762087348 and -7.762087348.

Subproblem 1

x + -4.5 = 7.762087348 Simplifying x + -4.5 = 7.762087348 Reorder the terms: -4.5 + x = 7.762087348 Solving -4.5 + x = 7.762087348 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 = 7.762087348 + 4.5 Combine like terms: -4.5 + 4.5 = 0.0 0.0 + x = 7.762087348 + 4.5 x = 7.762087348 + 4.5 Combine like terms: 7.762087348 + 4.5 = 12.262087348 x = 12.262087348 Simplifying x = 12.262087348

Subproblem 2

x + -4.5 = -7.762087348 Simplifying x + -4.5 = -7.762087348 Reorder the terms: -4.5 + x = -7.762087348 Solving -4.5 + x = -7.762087348 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 = -7.762087348 + 4.5 Combine like terms: -4.5 + 4.5 = 0.0 0.0 + x = -7.762087348 + 4.5 x = -7.762087348 + 4.5 Combine like terms: -7.762087348 + 4.5 = -3.262087348 x = -3.262087348 Simplifying x = -3.262087348

Solution

The solution to the problem is based on the solutions from the subproblems. x = {12.262087348, -3.262087348}

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