7x^2-x-80=87.2

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Solution for 7x^2-x-80=87.2 equation:


Simplifying
7x2 + -1x + -80 = 87.2

Reorder the terms:
-80 + -1x + 7x2 = 87.2

Solving
-80 + -1x + 7x2 = 87.2

Solving for variable 'x'.

Reorder the terms:
-80 + -87.2 + -1x + 7x2 = 87.2 + -87.2

Combine like terms: -80 + -87.2 = -167.2
-167.2 + -1x + 7x2 = 87.2 + -87.2

Combine like terms: 87.2 + -87.2 = 0.0
-167.2 + -1x + 7x2 = 0.0

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

Divide each side by '7'.
-23.88571429 + -0.1428571429x + x2 = 0.0

Move the constant term to the right:

Add '23.88571429' to each side of the equation.
-23.88571429 + -0.1428571429x + 23.88571429 + x2 = 0.0 + 23.88571429

Reorder the terms:
-23.88571429 + 23.88571429 + -0.1428571429x + x2 = 0.0 + 23.88571429

Combine like terms: -23.88571429 + 23.88571429 = 0.00000000
0.00000000 + -0.1428571429x + x2 = 0.0 + 23.88571429
-0.1428571429x + x2 = 0.0 + 23.88571429

Combine like terms: 0.0 + 23.88571429 = 23.88571429
-0.1428571429x + x2 = 23.88571429

The x term is -0.1428571429x.  Take half its coefficient (-0.07142857145).
Square it (0.005102040819) and add it to both sides.

Add '0.005102040819' to each side of the equation.
-0.1428571429x + 0.005102040819 + x2 = 23.88571429 + 0.005102040819

Reorder the terms:
0.005102040819 + -0.1428571429x + x2 = 23.88571429 + 0.005102040819

Combine like terms: 23.88571429 + 0.005102040819 = 23.890816330819
0.005102040819 + -0.1428571429x + x2 = 23.890816330819

Factor a perfect square on the left side:
(x + -0.07142857145)(x + -0.07142857145) = 23.890816330819

Calculate the square root of the right side: 4.887823271

Break this problem into two subproblems by setting 
(x + -0.07142857145) equal to 4.887823271 and -4.887823271.

Subproblem 1

x + -0.07142857145 = 4.887823271 Simplifying x + -0.07142857145 = 4.887823271 Reorder the terms: -0.07142857145 + x = 4.887823271 Solving -0.07142857145 + x = 4.887823271 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '0.07142857145' to each side of the equation. -0.07142857145 + 0.07142857145 + x = 4.887823271 + 0.07142857145 Combine like terms: -0.07142857145 + 0.07142857145 = 0.00000000000 0.00000000000 + x = 4.887823271 + 0.07142857145 x = 4.887823271 + 0.07142857145 Combine like terms: 4.887823271 + 0.07142857145 = 4.95925184245 x = 4.95925184245 Simplifying x = 4.95925184245

Subproblem 2

x + -0.07142857145 = -4.887823271 Simplifying x + -0.07142857145 = -4.887823271 Reorder the terms: -0.07142857145 + x = -4.887823271 Solving -0.07142857145 + x = -4.887823271 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '0.07142857145' to each side of the equation. -0.07142857145 + 0.07142857145 + x = -4.887823271 + 0.07142857145 Combine like terms: -0.07142857145 + 0.07142857145 = 0.00000000000 0.00000000000 + x = -4.887823271 + 0.07142857145 x = -4.887823271 + 0.07142857145 Combine like terms: -4.887823271 + 0.07142857145 = -4.81639469955 x = -4.81639469955 Simplifying x = -4.81639469955

Solution

The solution to the problem is based on the solutions from the subproblems. x = {4.95925184245, -4.81639469955}

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