2x^2-9x-87=0

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Solution for 2x^2-9x-87=0 equation:


Simplifying
2x2 + -9x + -87 = 0

Reorder the terms:
-87 + -9x + 2x2 = 0

Solving
-87 + -9x + 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 + -4.5x + x2 = 0

Move the constant term to the right:

Add '43.5' to each side of the equation.
-43.5 + -4.5x + 43.5 + x2 = 0 + 43.5

Reorder the terms:
-43.5 + 43.5 + -4.5x + x2 = 0 + 43.5

Combine like terms: -43.5 + 43.5 = 0.0
0.0 + -4.5x + x2 = 0 + 43.5
-4.5x + x2 = 0 + 43.5

Combine like terms: 0 + 43.5 = 43.5
-4.5x + x2 = 43.5

The x term is -4.5x.  Take half its coefficient (-2.25).
Square it (5.0625) and add it to both sides.

Add '5.0625' to each side of the equation.
-4.5x + 5.0625 + x2 = 43.5 + 5.0625

Reorder the terms:
5.0625 + -4.5x + x2 = 43.5 + 5.0625

Combine like terms: 43.5 + 5.0625 = 48.5625
5.0625 + -4.5x + x2 = 48.5625

Factor a perfect square on the left side:
(x + -2.25)(x + -2.25) = 48.5625

Calculate the square root of the right side: 6.968679932

Break this problem into two subproblems by setting 
(x + -2.25) equal to 6.968679932 and -6.968679932.

Subproblem 1

x + -2.25 = 6.968679932 Simplifying x + -2.25 = 6.968679932 Reorder the terms: -2.25 + x = 6.968679932 Solving -2.25 + x = 6.968679932 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '2.25' to each side of the equation. -2.25 + 2.25 + x = 6.968679932 + 2.25 Combine like terms: -2.25 + 2.25 = 0.00 0.00 + x = 6.968679932 + 2.25 x = 6.968679932 + 2.25 Combine like terms: 6.968679932 + 2.25 = 9.218679932 x = 9.218679932 Simplifying x = 9.218679932

Subproblem 2

x + -2.25 = -6.968679932 Simplifying x + -2.25 = -6.968679932 Reorder the terms: -2.25 + x = -6.968679932 Solving -2.25 + x = -6.968679932 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '2.25' to each side of the equation. -2.25 + 2.25 + x = -6.968679932 + 2.25 Combine like terms: -2.25 + 2.25 = 0.00 0.00 + x = -6.968679932 + 2.25 x = -6.968679932 + 2.25 Combine like terms: -6.968679932 + 2.25 = -4.718679932 x = -4.718679932 Simplifying x = -4.718679932

Solution

The solution to the problem is based on the solutions from the subproblems. x = {9.218679932, -4.718679932}

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