n^2-12n+21=0

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Solution for n^2-12n+21=0 equation:


Simplifying
n2 + -12n + 21 = 0

Reorder the terms:
21 + -12n + n2 = 0

Solving
21 + -12n + n2 = 0

Solving for variable 'n'.

Begin completing the square.

Move the constant term to the right:

Add '-21' to each side of the equation.
21 + -12n + -21 + n2 = 0 + -21

Reorder the terms:
21 + -21 + -12n + n2 = 0 + -21

Combine like terms: 21 + -21 = 0
0 + -12n + n2 = 0 + -21
-12n + n2 = 0 + -21

Combine like terms: 0 + -21 = -21
-12n + n2 = -21

The n term is -12n.  Take half its coefficient (-6).
Square it (36) and add it to both sides.

Add '36' to each side of the equation.
-12n + 36 + n2 = -21 + 36

Reorder the terms:
36 + -12n + n2 = -21 + 36

Combine like terms: -21 + 36 = 15
36 + -12n + n2 = 15

Factor a perfect square on the left side:
(n + -6)(n + -6) = 15

Calculate the square root of the right side: 3.872983346

Break this problem into two subproblems by setting 
(n + -6) equal to 3.872983346 and -3.872983346.

Subproblem 1

n + -6 = 3.872983346 Simplifying n + -6 = 3.872983346 Reorder the terms: -6 + n = 3.872983346 Solving -6 + n = 3.872983346 Solving for variable 'n'. Move all terms containing n to the left, all other terms to the right. Add '6' to each side of the equation. -6 + 6 + n = 3.872983346 + 6 Combine like terms: -6 + 6 = 0 0 + n = 3.872983346 + 6 n = 3.872983346 + 6 Combine like terms: 3.872983346 + 6 = 9.872983346 n = 9.872983346 Simplifying n = 9.872983346

Subproblem 2

n + -6 = -3.872983346 Simplifying n + -6 = -3.872983346 Reorder the terms: -6 + n = -3.872983346 Solving -6 + n = -3.872983346 Solving for variable 'n'. Move all terms containing n to the left, all other terms to the right. Add '6' to each side of the equation. -6 + 6 + n = -3.872983346 + 6 Combine like terms: -6 + 6 = 0 0 + n = -3.872983346 + 6 n = -3.872983346 + 6 Combine like terms: -3.872983346 + 6 = 2.127016654 n = 2.127016654 Simplifying n = 2.127016654

Solution

The solution to the problem is based on the solutions from the subproblems. n = {9.872983346, 2.127016654}

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