81n^2+18n-1=0

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Solution for 81n^2+18n-1=0 equation:


Simplifying
81n2 + 18n + -1 = 0

Reorder the terms:
-1 + 18n + 81n2 = 0

Solving
-1 + 18n + 81n2 = 0

Solving for variable 'n'.

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

Divide each side by '81'.
-0.01234567901 + 0.2222222222n + n2 = 0

Move the constant term to the right:

Add '0.01234567901' to each side of the equation.
-0.01234567901 + 0.2222222222n + 0.01234567901 + n2 = 0 + 0.01234567901

Reorder the terms:
-0.01234567901 + 0.01234567901 + 0.2222222222n + n2 = 0 + 0.01234567901

Combine like terms: -0.01234567901 + 0.01234567901 = 0.00000000000
0.00000000000 + 0.2222222222n + n2 = 0 + 0.01234567901
0.2222222222n + n2 = 0 + 0.01234567901

Combine like terms: 0 + 0.01234567901 = 0.01234567901
0.2222222222n + n2 = 0.01234567901

The n term is 0.2222222222n.  Take half its coefficient (0.1111111111).
Square it (0.01234567901) and add it to both sides.

Add '0.01234567901' to each side of the equation.
0.2222222222n + 0.01234567901 + n2 = 0.01234567901 + 0.01234567901

Reorder the terms:
0.01234567901 + 0.2222222222n + n2 = 0.01234567901 + 0.01234567901

Combine like terms: 0.01234567901 + 0.01234567901 = 0.02469135802
0.01234567901 + 0.2222222222n + n2 = 0.02469135802

Factor a perfect square on the left side:
(n + 0.1111111111)(n + 0.1111111111) = 0.02469135802

Calculate the square root of the right side: 0.15713484

Break this problem into two subproblems by setting 
(n + 0.1111111111) equal to 0.15713484 and -0.15713484.

Subproblem 1

n + 0.1111111111 = 0.15713484 Simplifying n + 0.1111111111 = 0.15713484 Reorder the terms: 0.1111111111 + n = 0.15713484 Solving 0.1111111111 + n = 0.15713484 Solving for variable 'n'. Move all terms containing n to the left, all other terms to the right. Add '-0.1111111111' to each side of the equation. 0.1111111111 + -0.1111111111 + n = 0.15713484 + -0.1111111111 Combine like terms: 0.1111111111 + -0.1111111111 = 0.0000000000 0.0000000000 + n = 0.15713484 + -0.1111111111 n = 0.15713484 + -0.1111111111 Combine like terms: 0.15713484 + -0.1111111111 = 0.0460237289 n = 0.0460237289 Simplifying n = 0.0460237289

Subproblem 2

n + 0.1111111111 = -0.15713484 Simplifying n + 0.1111111111 = -0.15713484 Reorder the terms: 0.1111111111 + n = -0.15713484 Solving 0.1111111111 + n = -0.15713484 Solving for variable 'n'. Move all terms containing n to the left, all other terms to the right. Add '-0.1111111111' to each side of the equation. 0.1111111111 + -0.1111111111 + n = -0.15713484 + -0.1111111111 Combine like terms: 0.1111111111 + -0.1111111111 = 0.0000000000 0.0000000000 + n = -0.15713484 + -0.1111111111 n = -0.15713484 + -0.1111111111 Combine like terms: -0.15713484 + -0.1111111111 = -0.2682459511 n = -0.2682459511 Simplifying n = -0.2682459511

Solution

The solution to the problem is based on the solutions from the subproblems. n = {0.0460237289, -0.2682459511}

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