7x^2-7x-8=0

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


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

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

Solving
-8 + -7x + 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 + -1x + x2 = 0

Move the constant term to the right:

Add '1.142857143' to each side of the equation.
-1.142857143 + -1x + 1.142857143 + x2 = 0 + 1.142857143

Reorder the terms:
-1.142857143 + 1.142857143 + -1x + x2 = 0 + 1.142857143

Combine like terms: -1.142857143 + 1.142857143 = 0.000000000
0.000000000 + -1x + x2 = 0 + 1.142857143
-1x + x2 = 0 + 1.142857143

Combine like terms: 0 + 1.142857143 = 1.142857143
-1x + x2 = 1.142857143

The x term is -1x.  Take half its coefficient (-0.5).
Square it (0.25) and add it to both sides.

Add '0.25' to each side of the equation.
-1x + 0.25 + x2 = 1.142857143 + 0.25

Reorder the terms:
0.25 + -1x + x2 = 1.142857143 + 0.25

Combine like terms: 1.142857143 + 0.25 = 1.392857143
0.25 + -1x + x2 = 1.392857143

Factor a perfect square on the left side:
(x + -0.5)(x + -0.5) = 1.392857143

Calculate the square root of the right side: 1.180193689

Break this problem into two subproblems by setting 
(x + -0.5) equal to 1.180193689 and -1.180193689.

Subproblem 1

x + -0.5 = 1.180193689 Simplifying x + -0.5 = 1.180193689 Reorder the terms: -0.5 + x = 1.180193689 Solving -0.5 + x = 1.180193689 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '0.5' to each side of the equation. -0.5 + 0.5 + x = 1.180193689 + 0.5 Combine like terms: -0.5 + 0.5 = 0.0 0.0 + x = 1.180193689 + 0.5 x = 1.180193689 + 0.5 Combine like terms: 1.180193689 + 0.5 = 1.680193689 x = 1.680193689 Simplifying x = 1.680193689

Subproblem 2

x + -0.5 = -1.180193689 Simplifying x + -0.5 = -1.180193689 Reorder the terms: -0.5 + x = -1.180193689 Solving -0.5 + x = -1.180193689 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '0.5' to each side of the equation. -0.5 + 0.5 + x = -1.180193689 + 0.5 Combine like terms: -0.5 + 0.5 = 0.0 0.0 + x = -1.180193689 + 0.5 x = -1.180193689 + 0.5 Combine like terms: -1.180193689 + 0.5 = -0.680193689 x = -0.680193689 Simplifying x = -0.680193689

Solution

The solution to the problem is based on the solutions from the subproblems. x = {1.680193689, -0.680193689}

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