n^2-3n-420=0

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Solution for n^2-3n-420=0 equation:


Simplifying
n2 + -3n + -420 = 0

Reorder the terms:
-420 + -3n + n2 = 0

Solving
-420 + -3n + n2 = 0

Solving for variable 'n'.

Begin completing the square.

Move the constant term to the right:

Add '420' to each side of the equation.
-420 + -3n + 420 + n2 = 0 + 420

Reorder the terms:
-420 + 420 + -3n + n2 = 0 + 420

Combine like terms: -420 + 420 = 0
0 + -3n + n2 = 0 + 420
-3n + n2 = 0 + 420

Combine like terms: 0 + 420 = 420
-3n + n2 = 420

The n term is -3n.  Take half its coefficient (-1.5).
Square it (2.25) and add it to both sides.

Add '2.25' to each side of the equation.
-3n + 2.25 + n2 = 420 + 2.25

Reorder the terms:
2.25 + -3n + n2 = 420 + 2.25

Combine like terms: 420 + 2.25 = 422.25
2.25 + -3n + n2 = 422.25

Factor a perfect square on the left side:
(n + -1.5)(n + -1.5) = 422.25

Calculate the square root of the right side: 20.548722588

Break this problem into two subproblems by setting 
(n + -1.5) equal to 20.548722588 and -20.548722588.

Subproblem 1

n + -1.5 = 20.548722588 Simplifying n + -1.5 = 20.548722588 Reorder the terms: -1.5 + n = 20.548722588 Solving -1.5 + n = 20.548722588 Solving for variable 'n'. Move all terms containing n to the left, all other terms to the right. Add '1.5' to each side of the equation. -1.5 + 1.5 + n = 20.548722588 + 1.5 Combine like terms: -1.5 + 1.5 = 0.0 0.0 + n = 20.548722588 + 1.5 n = 20.548722588 + 1.5 Combine like terms: 20.548722588 + 1.5 = 22.048722588 n = 22.048722588 Simplifying n = 22.048722588

Subproblem 2

n + -1.5 = -20.548722588 Simplifying n + -1.5 = -20.548722588 Reorder the terms: -1.5 + n = -20.548722588 Solving -1.5 + n = -20.548722588 Solving for variable 'n'. Move all terms containing n to the left, all other terms to the right. Add '1.5' to each side of the equation. -1.5 + 1.5 + n = -20.548722588 + 1.5 Combine like terms: -1.5 + 1.5 = 0.0 0.0 + n = -20.548722588 + 1.5 n = -20.548722588 + 1.5 Combine like terms: -20.548722588 + 1.5 = -19.048722588 n = -19.048722588 Simplifying n = -19.048722588

Solution

The solution to the problem is based on the solutions from the subproblems. n = {22.048722588, -19.048722588}

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