81x^2-13x-55=0

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Solution for 81x^2-13x-55=0 equation:


Simplifying
81x2 + -13x + -55 = 0

Reorder the terms:
-55 + -13x + 81x2 = 0

Solving
-55 + -13x + 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'.
-0.6790123457 + -0.1604938272x + x2 = 0

Move the constant term to the right:

Add '0.6790123457' to each side of the equation.
-0.6790123457 + -0.1604938272x + 0.6790123457 + x2 = 0 + 0.6790123457

Reorder the terms:
-0.6790123457 + 0.6790123457 + -0.1604938272x + x2 = 0 + 0.6790123457

Combine like terms: -0.6790123457 + 0.6790123457 = 0.0000000000
0.0000000000 + -0.1604938272x + x2 = 0 + 0.6790123457
-0.1604938272x + x2 = 0 + 0.6790123457

Combine like terms: 0 + 0.6790123457 = 0.6790123457
-0.1604938272x + x2 = 0.6790123457

The x term is -0.1604938272x.  Take half its coefficient (-0.0802469136).
Square it (0.006439567142) and add it to both sides.

Add '0.006439567142' to each side of the equation.
-0.1604938272x + 0.006439567142 + x2 = 0.6790123457 + 0.006439567142

Reorder the terms:
0.006439567142 + -0.1604938272x + x2 = 0.6790123457 + 0.006439567142

Combine like terms: 0.6790123457 + 0.006439567142 = 0.685451912842
0.006439567142 + -0.1604938272x + x2 = 0.685451912842

Factor a perfect square on the left side:
(x + -0.0802469136)(x + -0.0802469136) = 0.685451912842

Calculate the square root of the right side: 0.827920233

Break this problem into two subproblems by setting 
(x + -0.0802469136) equal to 0.827920233 and -0.827920233.

Subproblem 1

x + -0.0802469136 = 0.827920233 Simplifying x + -0.0802469136 = 0.827920233 Reorder the terms: -0.0802469136 + x = 0.827920233 Solving -0.0802469136 + x = 0.827920233 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '0.0802469136' to each side of the equation. -0.0802469136 + 0.0802469136 + x = 0.827920233 + 0.0802469136 Combine like terms: -0.0802469136 + 0.0802469136 = 0.0000000000 0.0000000000 + x = 0.827920233 + 0.0802469136 x = 0.827920233 + 0.0802469136 Combine like terms: 0.827920233 + 0.0802469136 = 0.9081671466 x = 0.9081671466 Simplifying x = 0.9081671466

Subproblem 2

x + -0.0802469136 = -0.827920233 Simplifying x + -0.0802469136 = -0.827920233 Reorder the terms: -0.0802469136 + x = -0.827920233 Solving -0.0802469136 + x = -0.827920233 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '0.0802469136' to each side of the equation. -0.0802469136 + 0.0802469136 + x = -0.827920233 + 0.0802469136 Combine like terms: -0.0802469136 + 0.0802469136 = 0.0000000000 0.0000000000 + x = -0.827920233 + 0.0802469136 x = -0.827920233 + 0.0802469136 Combine like terms: -0.827920233 + 0.0802469136 = -0.7476733194 x = -0.7476733194 Simplifying x = -0.7476733194

Solution

The solution to the problem is based on the solutions from the subproblems. x = {0.9081671466, -0.7476733194}

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