-2x^2+9x+8=0

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Solution for -2x^2+9x+8=0 equation:


Simplifying
-2x2 + 9x + 8 = 0

Reorder the terms:
8 + 9x + -2x2 = 0

Solving
8 + 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'.
-4 + -4.5x + x2 = 0

Move the constant term to the right:

Add '4' to each side of the equation.
-4 + -4.5x + 4 + x2 = 0 + 4

Reorder the terms:
-4 + 4 + -4.5x + x2 = 0 + 4

Combine like terms: -4 + 4 = 0
0 + -4.5x + x2 = 0 + 4
-4.5x + x2 = 0 + 4

Combine like terms: 0 + 4 = 4
-4.5x + x2 = 4

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 = 4 + 5.0625

Reorder the terms:
5.0625 + -4.5x + x2 = 4 + 5.0625

Combine like terms: 4 + 5.0625 = 9.0625
5.0625 + -4.5x + x2 = 9.0625

Factor a perfect square on the left side:
(x + -2.25)(x + -2.25) = 9.0625

Calculate the square root of the right side: 3.010398645

Break this problem into two subproblems by setting 
(x + -2.25) equal to 3.010398645 and -3.010398645.

Subproblem 1

x + -2.25 = 3.010398645 Simplifying x + -2.25 = 3.010398645 Reorder the terms: -2.25 + x = 3.010398645 Solving -2.25 + x = 3.010398645 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 = 3.010398645 + 2.25 Combine like terms: -2.25 + 2.25 = 0.00 0.00 + x = 3.010398645 + 2.25 x = 3.010398645 + 2.25 Combine like terms: 3.010398645 + 2.25 = 5.260398645 x = 5.260398645 Simplifying x = 5.260398645

Subproblem 2

x + -2.25 = -3.010398645 Simplifying x + -2.25 = -3.010398645 Reorder the terms: -2.25 + x = -3.010398645 Solving -2.25 + x = -3.010398645 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 = -3.010398645 + 2.25 Combine like terms: -2.25 + 2.25 = 0.00 0.00 + x = -3.010398645 + 2.25 x = -3.010398645 + 2.25 Combine like terms: -3.010398645 + 2.25 = -0.760398645 x = -0.760398645 Simplifying x = -0.760398645

Solution

The solution to the problem is based on the solutions from the subproblems. x = {5.260398645, -0.760398645}

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