(8x-1)(x+7)=9

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Solution for (8x-1)(x+7)=9 equation:


Simplifying
(8x + -1)(x + 7) = 9

Reorder the terms:
(-1 + 8x)(x + 7) = 9

Reorder the terms:
(-1 + 8x)(7 + x) = 9

Multiply (-1 + 8x) * (7 + x)
(-1(7 + x) + 8x * (7 + x)) = 9
((7 * -1 + x * -1) + 8x * (7 + x)) = 9
((-7 + -1x) + 8x * (7 + x)) = 9
(-7 + -1x + (7 * 8x + x * 8x)) = 9
(-7 + -1x + (56x + 8x2)) = 9

Combine like terms: -1x + 56x = 55x
(-7 + 55x + 8x2) = 9

Solving
-7 + 55x + 8x2 = 9

Solving for variable 'x'.

Reorder the terms:
-7 + -9 + 55x + 8x2 = 9 + -9

Combine like terms: -7 + -9 = -16
-16 + 55x + 8x2 = 9 + -9

Combine like terms: 9 + -9 = 0
-16 + 55x + 8x2 = 0

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

Divide each side by '8'.
-2 + 6.875x + x2 = 0

Move the constant term to the right:

Add '2' to each side of the equation.
-2 + 6.875x + 2 + x2 = 0 + 2

Reorder the terms:
-2 + 2 + 6.875x + x2 = 0 + 2

Combine like terms: -2 + 2 = 0
0 + 6.875x + x2 = 0 + 2
6.875x + x2 = 0 + 2

Combine like terms: 0 + 2 = 2
6.875x + x2 = 2

The x term is 6.875x.  Take half its coefficient (3.4375).
Square it (11.81640625) and add it to both sides.

Add '11.81640625' to each side of the equation.
6.875x + 11.81640625 + x2 = 2 + 11.81640625

Reorder the terms:
11.81640625 + 6.875x + x2 = 2 + 11.81640625

Combine like terms: 2 + 11.81640625 = 13.81640625
11.81640625 + 6.875x + x2 = 13.81640625

Factor a perfect square on the left side:
(x + 3.4375)(x + 3.4375) = 13.81640625

Calculate the square root of the right side: 3.717042675

Break this problem into two subproblems by setting 
(x + 3.4375) equal to 3.717042675 and -3.717042675.

Subproblem 1

x + 3.4375 = 3.717042675 Simplifying x + 3.4375 = 3.717042675 Reorder the terms: 3.4375 + x = 3.717042675 Solving 3.4375 + x = 3.717042675 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-3.4375' to each side of the equation. 3.4375 + -3.4375 + x = 3.717042675 + -3.4375 Combine like terms: 3.4375 + -3.4375 = 0.0000 0.0000 + x = 3.717042675 + -3.4375 x = 3.717042675 + -3.4375 Combine like terms: 3.717042675 + -3.4375 = 0.279542675 x = 0.279542675 Simplifying x = 0.279542675

Subproblem 2

x + 3.4375 = -3.717042675 Simplifying x + 3.4375 = -3.717042675 Reorder the terms: 3.4375 + x = -3.717042675 Solving 3.4375 + x = -3.717042675 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-3.4375' to each side of the equation. 3.4375 + -3.4375 + x = -3.717042675 + -3.4375 Combine like terms: 3.4375 + -3.4375 = 0.0000 0.0000 + x = -3.717042675 + -3.4375 x = -3.717042675 + -3.4375 Combine like terms: -3.717042675 + -3.4375 = -7.154542675 x = -7.154542675 Simplifying x = -7.154542675

Solution

The solution to the problem is based on the solutions from the subproblems. x = {0.279542675, -7.154542675}

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