2x^2+7x=8

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Solution for 2x^2+7x=8 equation:


Simplifying
2x2 + 7x = 8

Reorder the terms:
7x + 2x2 = 8

Solving
7x + 2x2 = 8

Solving for variable 'x'.

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

Combine like terms: 8 + -8 = 0
-8 + 7x + 2x2 = 0

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

Divide each side by '2'.
-4 + 3.5x + x2 = 0

Move the constant term to the right:

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

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

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

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

The x term is 3.5x.  Take half its coefficient (1.75).
Square it (3.0625) and add it to both sides.

Add '3.0625' to each side of the equation.
3.5x + 3.0625 + x2 = 4 + 3.0625

Reorder the terms:
3.0625 + 3.5x + x2 = 4 + 3.0625

Combine like terms: 4 + 3.0625 = 7.0625
3.0625 + 3.5x + x2 = 7.0625

Factor a perfect square on the left side:
(x + 1.75)(x + 1.75) = 7.0625

Calculate the square root of the right side: 2.657536453

Break this problem into two subproblems by setting 
(x + 1.75) equal to 2.657536453 and -2.657536453.

Subproblem 1

x + 1.75 = 2.657536453 Simplifying x + 1.75 = 2.657536453 Reorder the terms: 1.75 + x = 2.657536453 Solving 1.75 + x = 2.657536453 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-1.75' to each side of the equation. 1.75 + -1.75 + x = 2.657536453 + -1.75 Combine like terms: 1.75 + -1.75 = 0.00 0.00 + x = 2.657536453 + -1.75 x = 2.657536453 + -1.75 Combine like terms: 2.657536453 + -1.75 = 0.907536453 x = 0.907536453 Simplifying x = 0.907536453

Subproblem 2

x + 1.75 = -2.657536453 Simplifying x + 1.75 = -2.657536453 Reorder the terms: 1.75 + x = -2.657536453 Solving 1.75 + x = -2.657536453 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-1.75' to each side of the equation. 1.75 + -1.75 + x = -2.657536453 + -1.75 Combine like terms: 1.75 + -1.75 = 0.00 0.00 + x = -2.657536453 + -1.75 x = -2.657536453 + -1.75 Combine like terms: -2.657536453 + -1.75 = -4.407536453 x = -4.407536453 Simplifying x = -4.407536453

Solution

The solution to the problem is based on the solutions from the subproblems. x = {0.907536453, -4.407536453}

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