2x^2-18x-87=0

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Solution for 2x^2-18x-87=0 equation:


Simplifying
2x2 + -18x + -87 = 0

Reorder the terms:
-87 + -18x + 2x2 = 0

Solving
-87 + -18x + 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'.
-43.5 + -9x + x2 = 0

Move the constant term to the right:

Add '43.5' to each side of the equation.
-43.5 + -9x + 43.5 + x2 = 0 + 43.5

Reorder the terms:
-43.5 + 43.5 + -9x + x2 = 0 + 43.5

Combine like terms: -43.5 + 43.5 = 0.0
0.0 + -9x + x2 = 0 + 43.5
-9x + x2 = 0 + 43.5

Combine like terms: 0 + 43.5 = 43.5
-9x + x2 = 43.5

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 = 43.5 + 20.25

Reorder the terms:
20.25 + -9x + x2 = 43.5 + 20.25

Combine like terms: 43.5 + 20.25 = 63.75
20.25 + -9x + x2 = 63.75

Factor a perfect square on the left side:
(x + -4.5)(x + -4.5) = 63.75

Calculate the square root of the right side: 7.984359711

Break this problem into two subproblems by setting 
(x + -4.5) equal to 7.984359711 and -7.984359711.

Subproblem 1

x + -4.5 = 7.984359711 Simplifying x + -4.5 = 7.984359711 Reorder the terms: -4.5 + x = 7.984359711 Solving -4.5 + x = 7.984359711 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 = 7.984359711 + 4.5 Combine like terms: -4.5 + 4.5 = 0.0 0.0 + x = 7.984359711 + 4.5 x = 7.984359711 + 4.5 Combine like terms: 7.984359711 + 4.5 = 12.484359711 x = 12.484359711 Simplifying x = 12.484359711

Subproblem 2

x + -4.5 = -7.984359711 Simplifying x + -4.5 = -7.984359711 Reorder the terms: -4.5 + x = -7.984359711 Solving -4.5 + x = -7.984359711 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 = -7.984359711 + 4.5 Combine like terms: -4.5 + 4.5 = 0.0 0.0 + x = -7.984359711 + 4.5 x = -7.984359711 + 4.5 Combine like terms: -7.984359711 + 4.5 = -3.484359711 x = -3.484359711 Simplifying x = -3.484359711

Solution

The solution to the problem is based on the solutions from the subproblems. x = {12.484359711, -3.484359711}

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