2x^2-90x-81=0

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Solution for 2x^2-90x-81=0 equation:


Simplifying
2x2 + -90x + -81 = 0

Reorder the terms:
-81 + -90x + 2x2 = 0

Solving
-81 + -90x + 2x2 = 0

Solving for variable 'x'.

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

Divide each side by '2'.
-40.5 + -45x + x2 = 0

Move the constant term to the right:

Add '40.5' to each side of the equation.
-40.5 + -45x + 40.5 + x2 = 0 + 40.5

Reorder the terms:
-40.5 + 40.5 + -45x + x2 = 0 + 40.5

Combine like terms: -40.5 + 40.5 = 0.0
0.0 + -45x + x2 = 0 + 40.5
-45x + x2 = 0 + 40.5

Combine like terms: 0 + 40.5 = 40.5
-45x + x2 = 40.5

The x term is -45x.  Take half its coefficient (-22.5).
Square it (506.25) and add it to both sides.

Add '506.25' to each side of the equation.
-45x + 506.25 + x2 = 40.5 + 506.25

Reorder the terms:
506.25 + -45x + x2 = 40.5 + 506.25

Combine like terms: 40.5 + 506.25 = 546.75
506.25 + -45x + x2 = 546.75

Factor a perfect square on the left side:
(x + -22.5)(x + -22.5) = 546.75

Calculate the square root of the right side: 23.382685902

Break this problem into two subproblems by setting 
(x + -22.5) equal to 23.382685902 and -23.382685902.

Subproblem 1

x + -22.5 = 23.382685902 Simplifying x + -22.5 = 23.382685902 Reorder the terms: -22.5 + x = 23.382685902 Solving -22.5 + x = 23.382685902 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '22.5' to each side of the equation. -22.5 + 22.5 + x = 23.382685902 + 22.5 Combine like terms: -22.5 + 22.5 = 0.0 0.0 + x = 23.382685902 + 22.5 x = 23.382685902 + 22.5 Combine like terms: 23.382685902 + 22.5 = 45.882685902 x = 45.882685902 Simplifying x = 45.882685902

Subproblem 2

x + -22.5 = -23.382685902 Simplifying x + -22.5 = -23.382685902 Reorder the terms: -22.5 + x = -23.382685902 Solving -22.5 + x = -23.382685902 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '22.5' to each side of the equation. -22.5 + 22.5 + x = -23.382685902 + 22.5 Combine like terms: -22.5 + 22.5 = 0.0 0.0 + x = -23.382685902 + 22.5 x = -23.382685902 + 22.5 Combine like terms: -23.382685902 + 22.5 = -0.882685902 x = -0.882685902 Simplifying x = -0.882685902

Solution

The solution to the problem is based on the solutions from the subproblems. x = {45.882685902, -0.882685902}

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