2n^2-9=18n

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Solution for 2n^2-9=18n equation:


Simplifying
2n2 + -9 = 18n

Reorder the terms:
-9 + 2n2 = 18n

Solving
-9 + 2n2 = 18n

Solving for variable 'n'.

Reorder the terms:
-9 + -18n + 2n2 = 18n + -18n

Combine like terms: 18n + -18n = 0
-9 + -18n + 2n2 = 0

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

Divide each side by '2'.
-4.5 + -9n + n2 = 0

Move the constant term to the right:

Add '4.5' to each side of the equation.
-4.5 + -9n + 4.5 + n2 = 0 + 4.5

Reorder the terms:
-4.5 + 4.5 + -9n + n2 = 0 + 4.5

Combine like terms: -4.5 + 4.5 = 0.0
0.0 + -9n + n2 = 0 + 4.5
-9n + n2 = 0 + 4.5

Combine like terms: 0 + 4.5 = 4.5
-9n + n2 = 4.5

The n term is -9n.  Take half its coefficient (-4.5).
Square it (20.25) and add it to both sides.

Add '20.25' to each side of the equation.
-9n + 20.25 + n2 = 4.5 + 20.25

Reorder the terms:
20.25 + -9n + n2 = 4.5 + 20.25

Combine like terms: 4.5 + 20.25 = 24.75
20.25 + -9n + n2 = 24.75

Factor a perfect square on the left side:
(n + -4.5)(n + -4.5) = 24.75

Calculate the square root of the right side: 4.974937186

Break this problem into two subproblems by setting 
(n + -4.5) equal to 4.974937186 and -4.974937186.

Subproblem 1

n + -4.5 = 4.974937186 Simplifying n + -4.5 = 4.974937186 Reorder the terms: -4.5 + n = 4.974937186 Solving -4.5 + n = 4.974937186 Solving for variable 'n'. Move all terms containing n to the left, all other terms to the right. Add '4.5' to each side of the equation. -4.5 + 4.5 + n = 4.974937186 + 4.5 Combine like terms: -4.5 + 4.5 = 0.0 0.0 + n = 4.974937186 + 4.5 n = 4.974937186 + 4.5 Combine like terms: 4.974937186 + 4.5 = 9.474937186 n = 9.474937186 Simplifying n = 9.474937186

Subproblem 2

n + -4.5 = -4.974937186 Simplifying n + -4.5 = -4.974937186 Reorder the terms: -4.5 + n = -4.974937186 Solving -4.5 + n = -4.974937186 Solving for variable 'n'. Move all terms containing n to the left, all other terms to the right. Add '4.5' to each side of the equation. -4.5 + 4.5 + n = -4.974937186 + 4.5 Combine like terms: -4.5 + 4.5 = 0.0 0.0 + n = -4.974937186 + 4.5 n = -4.974937186 + 4.5 Combine like terms: -4.974937186 + 4.5 = -0.474937186 n = -0.474937186 Simplifying n = -0.474937186

Solution

The solution to the problem is based on the solutions from the subproblems. n = {9.474937186, -0.474937186}

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