5=-2x^2+8x

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Solution for 5=-2x^2+8x equation:


Simplifying
5 = -2x2 + 8x

Reorder the terms:
5 = 8x + -2x2

Solving
5 = 8x + -2x2

Solving for variable 'x'.

Reorder the terms:
5 + -8x + 2x2 = 8x + -8x + -2x2 + 2x2

Combine like terms: 8x + -8x = 0
5 + -8x + 2x2 = 0 + -2x2 + 2x2
5 + -8x + 2x2 = -2x2 + 2x2

Combine like terms: -2x2 + 2x2 = 0
5 + -8x + 2x2 = 0

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

Divide each side by '2'.
2.5 + -4x + x2 = 0

Move the constant term to the right:

Add '-2.5' to each side of the equation.
2.5 + -4x + -2.5 + x2 = 0 + -2.5

Reorder the terms:
2.5 + -2.5 + -4x + x2 = 0 + -2.5

Combine like terms: 2.5 + -2.5 = 0.0
0.0 + -4x + x2 = 0 + -2.5
-4x + x2 = 0 + -2.5

Combine like terms: 0 + -2.5 = -2.5
-4x + x2 = -2.5

The x term is -4x.  Take half its coefficient (-2).
Square it (4) and add it to both sides.

Add '4' to each side of the equation.
-4x + 4 + x2 = -2.5 + 4

Reorder the terms:
4 + -4x + x2 = -2.5 + 4

Combine like terms: -2.5 + 4 = 1.5
4 + -4x + x2 = 1.5

Factor a perfect square on the left side:
(x + -2)(x + -2) = 1.5

Calculate the square root of the right side: 1.224744871

Break this problem into two subproblems by setting 
(x + -2) equal to 1.224744871 and -1.224744871.

Subproblem 1

x + -2 = 1.224744871 Simplifying x + -2 = 1.224744871 Reorder the terms: -2 + x = 1.224744871 Solving -2 + x = 1.224744871 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '2' to each side of the equation. -2 + 2 + x = 1.224744871 + 2 Combine like terms: -2 + 2 = 0 0 + x = 1.224744871 + 2 x = 1.224744871 + 2 Combine like terms: 1.224744871 + 2 = 3.224744871 x = 3.224744871 Simplifying x = 3.224744871

Subproblem 2

x + -2 = -1.224744871 Simplifying x + -2 = -1.224744871 Reorder the terms: -2 + x = -1.224744871 Solving -2 + x = -1.224744871 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '2' to each side of the equation. -2 + 2 + x = -1.224744871 + 2 Combine like terms: -2 + 2 = 0 0 + x = -1.224744871 + 2 x = -1.224744871 + 2 Combine like terms: -1.224744871 + 2 = 0.775255129 x = 0.775255129 Simplifying x = 0.775255129

Solution

The solution to the problem is based on the solutions from the subproblems. x = {3.224744871, 0.775255129}

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