81x^2+7x-56=0

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Solution for 81x^2+7x-56=0 equation:


Simplifying
81x2 + 7x + -56 = 0

Reorder the terms:
-56 + 7x + 81x2 = 0

Solving
-56 + 7x + 81x2 = 0

Solving for variable 'x'.

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

Divide each side by '81'.
-0.6913580247 + 0.08641975309x + x2 = 0

Move the constant term to the right:

Add '0.6913580247' to each side of the equation.
-0.6913580247 + 0.08641975309x + 0.6913580247 + x2 = 0 + 0.6913580247

Reorder the terms:
-0.6913580247 + 0.6913580247 + 0.08641975309x + x2 = 0 + 0.6913580247

Combine like terms: -0.6913580247 + 0.6913580247 = 0.0000000000
0.0000000000 + 0.08641975309x + x2 = 0 + 0.6913580247
0.08641975309x + x2 = 0 + 0.6913580247

Combine like terms: 0 + 0.6913580247 = 0.6913580247
0.08641975309x + x2 = 0.6913580247

The x term is 0.08641975309x.  Take half its coefficient (0.04320987655).
Square it (0.001867093431) and add it to both sides.

Add '0.001867093431' to each side of the equation.
0.08641975309x + 0.001867093431 + x2 = 0.6913580247 + 0.001867093431

Reorder the terms:
0.001867093431 + 0.08641975309x + x2 = 0.6913580247 + 0.001867093431

Combine like terms: 0.6913580247 + 0.001867093431 = 0.693225118131
0.001867093431 + 0.08641975309x + x2 = 0.693225118131

Factor a perfect square on the left side:
(x + 0.04320987655)(x + 0.04320987655) = 0.693225118131

Calculate the square root of the right side: 0.832601416

Break this problem into two subproblems by setting 
(x + 0.04320987655) equal to 0.832601416 and -0.832601416.

Subproblem 1

x + 0.04320987655 = 0.832601416 Simplifying x + 0.04320987655 = 0.832601416 Reorder the terms: 0.04320987655 + x = 0.832601416 Solving 0.04320987655 + x = 0.832601416 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.04320987655' to each side of the equation. 0.04320987655 + -0.04320987655 + x = 0.832601416 + -0.04320987655 Combine like terms: 0.04320987655 + -0.04320987655 = 0.00000000000 0.00000000000 + x = 0.832601416 + -0.04320987655 x = 0.832601416 + -0.04320987655 Combine like terms: 0.832601416 + -0.04320987655 = 0.78939153945 x = 0.78939153945 Simplifying x = 0.78939153945

Subproblem 2

x + 0.04320987655 = -0.832601416 Simplifying x + 0.04320987655 = -0.832601416 Reorder the terms: 0.04320987655 + x = -0.832601416 Solving 0.04320987655 + x = -0.832601416 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.04320987655' to each side of the equation. 0.04320987655 + -0.04320987655 + x = -0.832601416 + -0.04320987655 Combine like terms: 0.04320987655 + -0.04320987655 = 0.00000000000 0.00000000000 + x = -0.832601416 + -0.04320987655 x = -0.832601416 + -0.04320987655 Combine like terms: -0.832601416 + -0.04320987655 = -0.87581129255 x = -0.87581129255 Simplifying x = -0.87581129255

Solution

The solution to the problem is based on the solutions from the subproblems. x = {0.78939153945, -0.87581129255}

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