7x^2-4x-80=0

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Solution for 7x^2-4x-80=0 equation:


Simplifying
7x2 + -4x + -80 = 0

Reorder the terms:
-80 + -4x + 7x2 = 0

Solving
-80 + -4x + 7x2 = 0

Solving for variable 'x'.

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

Divide each side by '7'.
-11.42857143 + -0.5714285714x + x2 = 0

Move the constant term to the right:

Add '11.42857143' to each side of the equation.
-11.42857143 + -0.5714285714x + 11.42857143 + x2 = 0 + 11.42857143

Reorder the terms:
-11.42857143 + 11.42857143 + -0.5714285714x + x2 = 0 + 11.42857143

Combine like terms: -11.42857143 + 11.42857143 = 0.00000000
0.00000000 + -0.5714285714x + x2 = 0 + 11.42857143
-0.5714285714x + x2 = 0 + 11.42857143

Combine like terms: 0 + 11.42857143 = 11.42857143
-0.5714285714x + x2 = 11.42857143

The x term is -0.5714285714x.  Take half its coefficient (-0.2857142857).
Square it (0.08163265305) and add it to both sides.

Add '0.08163265305' to each side of the equation.
-0.5714285714x + 0.08163265305 + x2 = 11.42857143 + 0.08163265305

Reorder the terms:
0.08163265305 + -0.5714285714x + x2 = 11.42857143 + 0.08163265305

Combine like terms: 11.42857143 + 0.08163265305 = 11.51020408305
0.08163265305 + -0.5714285714x + x2 = 11.51020408305

Factor a perfect square on the left side:
(x + -0.2857142857)(x + -0.2857142857) = 11.51020408305

Calculate the square root of the right side: 3.392669168

Break this problem into two subproblems by setting 
(x + -0.2857142857) equal to 3.392669168 and -3.392669168.

Subproblem 1

x + -0.2857142857 = 3.392669168 Simplifying x + -0.2857142857 = 3.392669168 Reorder the terms: -0.2857142857 + x = 3.392669168 Solving -0.2857142857 + x = 3.392669168 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '0.2857142857' to each side of the equation. -0.2857142857 + 0.2857142857 + x = 3.392669168 + 0.2857142857 Combine like terms: -0.2857142857 + 0.2857142857 = 0.0000000000 0.0000000000 + x = 3.392669168 + 0.2857142857 x = 3.392669168 + 0.2857142857 Combine like terms: 3.392669168 + 0.2857142857 = 3.6783834537 x = 3.6783834537 Simplifying x = 3.6783834537

Subproblem 2

x + -0.2857142857 = -3.392669168 Simplifying x + -0.2857142857 = -3.392669168 Reorder the terms: -0.2857142857 + x = -3.392669168 Solving -0.2857142857 + x = -3.392669168 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '0.2857142857' to each side of the equation. -0.2857142857 + 0.2857142857 + x = -3.392669168 + 0.2857142857 Combine like terms: -0.2857142857 + 0.2857142857 = 0.0000000000 0.0000000000 + x = -3.392669168 + 0.2857142857 x = -3.392669168 + 0.2857142857 Combine like terms: -3.392669168 + 0.2857142857 = -3.1069548823 x = -3.1069548823 Simplifying x = -3.1069548823

Solution

The solution to the problem is based on the solutions from the subproblems. x = {3.6783834537, -3.1069548823}

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