2x*x+8x-7=0

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Solution for 2x*x+8x-7=0 equation:


Simplifying
2x * x + 8x + -7 = 0

Multiply x * x
2x2 + 8x + -7 = 0

Reorder the terms:
-7 + 8x + 2x2 = 0

Solving
-7 + 8x + 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'.
-3.5 + 4x + x2 = 0

Move the constant term to the right:

Add '3.5' to each side of the equation.
-3.5 + 4x + 3.5 + x2 = 0 + 3.5

Reorder the terms:
-3.5 + 3.5 + 4x + x2 = 0 + 3.5

Combine like terms: -3.5 + 3.5 = 0.0
0.0 + 4x + x2 = 0 + 3.5
4x + x2 = 0 + 3.5

Combine like terms: 0 + 3.5 = 3.5
4x + x2 = 3.5

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 = 3.5 + 4

Reorder the terms:
4 + 4x + x2 = 3.5 + 4

Combine like terms: 3.5 + 4 = 7.5
4 + 4x + x2 = 7.5

Factor a perfect square on the left side:
(x + 2)(x + 2) = 7.5

Calculate the square root of the right side: 2.738612788

Break this problem into two subproblems by setting 
(x + 2) equal to 2.738612788 and -2.738612788.

Subproblem 1

x + 2 = 2.738612788 Simplifying x + 2 = 2.738612788 Reorder the terms: 2 + x = 2.738612788 Solving 2 + x = 2.738612788 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 = 2.738612788 + -2 Combine like terms: 2 + -2 = 0 0 + x = 2.738612788 + -2 x = 2.738612788 + -2 Combine like terms: 2.738612788 + -2 = 0.738612788 x = 0.738612788 Simplifying x = 0.738612788

Subproblem 2

x + 2 = -2.738612788 Simplifying x + 2 = -2.738612788 Reorder the terms: 2 + x = -2.738612788 Solving 2 + x = -2.738612788 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 = -2.738612788 + -2 Combine like terms: 2 + -2 = 0 0 + x = -2.738612788 + -2 x = -2.738612788 + -2 Combine like terms: -2.738612788 + -2 = -4.738612788 x = -4.738612788 Simplifying x = -4.738612788

Solution

The solution to the problem is based on the solutions from the subproblems. x = {0.738612788, -4.738612788}

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