7x^2-11x-8=0

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Solution for 7x^2-11x-8=0 equation:


Simplifying
7x2 + -11x + -8 = 0

Reorder the terms:
-8 + -11x + 7x2 = 0

Solving
-8 + -11x + 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 + -1.571428571x + x2 = 0

Move the constant term to the right:

Add '1.142857143' to each side of the equation.
-1.142857143 + -1.571428571x + 1.142857143 + x2 = 0 + 1.142857143

Reorder the terms:
-1.142857143 + 1.142857143 + -1.571428571x + x2 = 0 + 1.142857143

Combine like terms: -1.142857143 + 1.142857143 = 0.000000000
0.000000000 + -1.571428571x + x2 = 0 + 1.142857143
-1.571428571x + x2 = 0 + 1.142857143

Combine like terms: 0 + 1.142857143 = 1.142857143
-1.571428571x + x2 = 1.142857143

The x term is -1.571428571x.  Take half its coefficient (-0.7857142855).
Square it (0.6173469384) and add it to both sides.

Add '0.6173469384' to each side of the equation.
-1.571428571x + 0.6173469384 + x2 = 1.142857143 + 0.6173469384

Reorder the terms:
0.6173469384 + -1.571428571x + x2 = 1.142857143 + 0.6173469384

Combine like terms: 1.142857143 + 0.6173469384 = 1.7602040814
0.6173469384 + -1.571428571x + x2 = 1.7602040814

Factor a perfect square on the left side:
(x + -0.7857142855)(x + -0.7857142855) = 1.7602040814

Calculate the square root of the right side: 1.32672683

Break this problem into two subproblems by setting 
(x + -0.7857142855) equal to 1.32672683 and -1.32672683.

Subproblem 1

x + -0.7857142855 = 1.32672683 Simplifying x + -0.7857142855 = 1.32672683 Reorder the terms: -0.7857142855 + x = 1.32672683 Solving -0.7857142855 + x = 1.32672683 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '0.7857142855' to each side of the equation. -0.7857142855 + 0.7857142855 + x = 1.32672683 + 0.7857142855 Combine like terms: -0.7857142855 + 0.7857142855 = 0.0000000000 0.0000000000 + x = 1.32672683 + 0.7857142855 x = 1.32672683 + 0.7857142855 Combine like terms: 1.32672683 + 0.7857142855 = 2.1124411155 x = 2.1124411155 Simplifying x = 2.1124411155

Subproblem 2

x + -0.7857142855 = -1.32672683 Simplifying x + -0.7857142855 = -1.32672683 Reorder the terms: -0.7857142855 + x = -1.32672683 Solving -0.7857142855 + x = -1.32672683 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '0.7857142855' to each side of the equation. -0.7857142855 + 0.7857142855 + x = -1.32672683 + 0.7857142855 Combine like terms: -0.7857142855 + 0.7857142855 = 0.0000000000 0.0000000000 + x = -1.32672683 + 0.7857142855 x = -1.32672683 + 0.7857142855 Combine like terms: -1.32672683 + 0.7857142855 = -0.5410125445 x = -0.5410125445 Simplifying x = -0.5410125445

Solution

The solution to the problem is based on the solutions from the subproblems. x = {2.1124411155, -0.5410125445}

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