7x^2-12x-8=0

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Solution for 7x^2-12x-8=0 equation:


Simplifying
7x2 + -12x + -8 = 0

Reorder the terms:
-8 + -12x + 7x2 = 0

Solving
-8 + -12x + 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'.
-1.142857143 + -1.714285714x + x2 = 0

Move the constant term to the right:

Add '1.142857143' to each side of the equation.
-1.142857143 + -1.714285714x + 1.142857143 + x2 = 0 + 1.142857143

Reorder the terms:
-1.142857143 + 1.142857143 + -1.714285714x + x2 = 0 + 1.142857143

Combine like terms: -1.142857143 + 1.142857143 = 0.000000000
0.000000000 + -1.714285714x + x2 = 0 + 1.142857143
-1.714285714x + x2 = 0 + 1.142857143

Combine like terms: 0 + 1.142857143 = 1.142857143
-1.714285714x + x2 = 1.142857143

The x term is -1.714285714x.  Take half its coefficient (-0.857142857).
Square it (0.7346938773) and add it to both sides.

Add '0.7346938773' to each side of the equation.
-1.714285714x + 0.7346938773 + x2 = 1.142857143 + 0.7346938773

Reorder the terms:
0.7346938773 + -1.714285714x + x2 = 1.142857143 + 0.7346938773

Combine like terms: 1.142857143 + 0.7346938773 = 1.8775510203
0.7346938773 + -1.714285714x + x2 = 1.8775510203

Factor a perfect square on the left side:
(x + -0.857142857)(x + -0.857142857) = 1.8775510203

Calculate the square root of the right side: 1.370237578

Break this problem into two subproblems by setting 
(x + -0.857142857) equal to 1.370237578 and -1.370237578.

Subproblem 1

x + -0.857142857 = 1.370237578 Simplifying x + -0.857142857 = 1.370237578 Reorder the terms: -0.857142857 + x = 1.370237578 Solving -0.857142857 + x = 1.370237578 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '0.857142857' to each side of the equation. -0.857142857 + 0.857142857 + x = 1.370237578 + 0.857142857 Combine like terms: -0.857142857 + 0.857142857 = 0.000000000 0.000000000 + x = 1.370237578 + 0.857142857 x = 1.370237578 + 0.857142857 Combine like terms: 1.370237578 + 0.857142857 = 2.227380435 x = 2.227380435 Simplifying x = 2.227380435

Subproblem 2

x + -0.857142857 = -1.370237578 Simplifying x + -0.857142857 = -1.370237578 Reorder the terms: -0.857142857 + x = -1.370237578 Solving -0.857142857 + x = -1.370237578 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '0.857142857' to each side of the equation. -0.857142857 + 0.857142857 + x = -1.370237578 + 0.857142857 Combine like terms: -0.857142857 + 0.857142857 = 0.000000000 0.000000000 + x = -1.370237578 + 0.857142857 x = -1.370237578 + 0.857142857 Combine like terms: -1.370237578 + 0.857142857 = -0.513094721 x = -0.513094721 Simplifying x = -0.513094721

Solution

The solution to the problem is based on the solutions from the subproblems. x = {2.227380435, -0.513094721}

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