-2x^2+2x+15=0

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Solution for -2x^2+2x+15=0 equation:


Simplifying
-2x2 + 2x + 15 = 0

Reorder the terms:
15 + 2x + -2x2 = 0

Solving
15 + 2x + -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'.
-7.5 + -1x + x2 = 0

Move the constant term to the right:

Add '7.5' to each side of the equation.
-7.5 + -1x + 7.5 + x2 = 0 + 7.5

Reorder the terms:
-7.5 + 7.5 + -1x + x2 = 0 + 7.5

Combine like terms: -7.5 + 7.5 = 0.0
0.0 + -1x + x2 = 0 + 7.5
-1x + x2 = 0 + 7.5

Combine like terms: 0 + 7.5 = 7.5
-1x + x2 = 7.5

The x term is -1x.  Take half its coefficient (-0.5).
Square it (0.25) and add it to both sides.

Add '0.25' to each side of the equation.
-1x + 0.25 + x2 = 7.5 + 0.25

Reorder the terms:
0.25 + -1x + x2 = 7.5 + 0.25

Combine like terms: 7.5 + 0.25 = 7.75
0.25 + -1x + x2 = 7.75

Factor a perfect square on the left side:
(x + -0.5)(x + -0.5) = 7.75

Calculate the square root of the right side: 2.783882181

Break this problem into two subproblems by setting 
(x + -0.5) equal to 2.783882181 and -2.783882181.

Subproblem 1

x + -0.5 = 2.783882181 Simplifying x + -0.5 = 2.783882181 Reorder the terms: -0.5 + x = 2.783882181 Solving -0.5 + x = 2.783882181 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '0.5' to each side of the equation. -0.5 + 0.5 + x = 2.783882181 + 0.5 Combine like terms: -0.5 + 0.5 = 0.0 0.0 + x = 2.783882181 + 0.5 x = 2.783882181 + 0.5 Combine like terms: 2.783882181 + 0.5 = 3.283882181 x = 3.283882181 Simplifying x = 3.283882181

Subproblem 2

x + -0.5 = -2.783882181 Simplifying x + -0.5 = -2.783882181 Reorder the terms: -0.5 + x = -2.783882181 Solving -0.5 + x = -2.783882181 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '0.5' to each side of the equation. -0.5 + 0.5 + x = -2.783882181 + 0.5 Combine like terms: -0.5 + 0.5 = 0.0 0.0 + x = -2.783882181 + 0.5 x = -2.783882181 + 0.5 Combine like terms: -2.783882181 + 0.5 = -2.283882181 x = -2.283882181 Simplifying x = -2.283882181

Solution

The solution to the problem is based on the solutions from the subproblems. x = {3.283882181, -2.283882181}

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