7n^2-9n-1=0

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Solution for 7n^2-9n-1=0 equation:


Simplifying
7n2 + -9n + -1 = 0

Reorder the terms:
-1 + -9n + 7n2 = 0

Solving
-1 + -9n + 7n2 = 0

Solving for variable 'n'.

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

Divide each side by '7'.
-0.1428571429 + -1.285714286n + n2 = 0

Move the constant term to the right:

Add '0.1428571429' to each side of the equation.
-0.1428571429 + -1.285714286n + 0.1428571429 + n2 = 0 + 0.1428571429

Reorder the terms:
-0.1428571429 + 0.1428571429 + -1.285714286n + n2 = 0 + 0.1428571429

Combine like terms: -0.1428571429 + 0.1428571429 = 0.0000000000
0.0000000000 + -1.285714286n + n2 = 0 + 0.1428571429
-1.285714286n + n2 = 0 + 0.1428571429

Combine like terms: 0 + 0.1428571429 = 0.1428571429
-1.285714286n + n2 = 0.1428571429

The n term is -1.285714286n.  Take half its coefficient (-0.642857143).
Square it (0.4132653063) and add it to both sides.

Add '0.4132653063' to each side of the equation.
-1.285714286n + 0.4132653063 + n2 = 0.1428571429 + 0.4132653063

Reorder the terms:
0.4132653063 + -1.285714286n + n2 = 0.1428571429 + 0.4132653063

Combine like terms: 0.1428571429 + 0.4132653063 = 0.5561224492
0.4132653063 + -1.285714286n + n2 = 0.5561224492

Factor a perfect square on the left side:
(n + -0.642857143)(n + -0.642857143) = 0.5561224492

Calculate the square root of the right side: 0.745736179

Break this problem into two subproblems by setting 
(n + -0.642857143) equal to 0.745736179 and -0.745736179.

Subproblem 1

n + -0.642857143 = 0.745736179 Simplifying n + -0.642857143 = 0.745736179 Reorder the terms: -0.642857143 + n = 0.745736179 Solving -0.642857143 + n = 0.745736179 Solving for variable 'n'. Move all terms containing n to the left, all other terms to the right. Add '0.642857143' to each side of the equation. -0.642857143 + 0.642857143 + n = 0.745736179 + 0.642857143 Combine like terms: -0.642857143 + 0.642857143 = 0.000000000 0.000000000 + n = 0.745736179 + 0.642857143 n = 0.745736179 + 0.642857143 Combine like terms: 0.745736179 + 0.642857143 = 1.388593322 n = 1.388593322 Simplifying n = 1.388593322

Subproblem 2

n + -0.642857143 = -0.745736179 Simplifying n + -0.642857143 = -0.745736179 Reorder the terms: -0.642857143 + n = -0.745736179 Solving -0.642857143 + n = -0.745736179 Solving for variable 'n'. Move all terms containing n to the left, all other terms to the right. Add '0.642857143' to each side of the equation. -0.642857143 + 0.642857143 + n = -0.745736179 + 0.642857143 Combine like terms: -0.642857143 + 0.642857143 = 0.000000000 0.000000000 + n = -0.745736179 + 0.642857143 n = -0.745736179 + 0.642857143 Combine like terms: -0.745736179 + 0.642857143 = -0.102879036 n = -0.102879036 Simplifying n = -0.102879036

Solution

The solution to the problem is based on the solutions from the subproblems. n = {1.388593322, -0.102879036}

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