12n^2-21=-9n

Solution for 12n^2-21=-9n equation:

Simplifying
12n2 + -21 = -9n

Reorder the terms:
-21 + 12n2 = -9n

Solving
-21 + 12n2 = -9n

Solving for variable 'n'.

Reorder the terms:
-21 + 9n + 12n2 = -9n + 9n

Combine like terms: -9n + 9n = 0
-21 + 9n + 12n2 = 0

Factor out the Greatest Common Factor (GCF), '3'.
3(-7 + 3n + 4n2) = 0

Factor a trinomial.
3((-7 + -4n)(1 + -1n)) = 0

Ignore the factor 3.
Subproblem 1
Set the factor '(-7 + -4n)' equal to zero and attempt to solve:

Simplifying
-7 + -4n = 0

Solving
-7 + -4n = 0

Move all terms containing n to the left, all other terms to the right.

Add '7' to each side of the equation.
-7 + 7 + -4n = 0 + 7

Combine like terms: -7 + 7 = 0
0 + -4n = 0 + 7
-4n = 0 + 7

Combine like terms: 0 + 7 = 7
-4n = 7

Divide each side by '-4'.
n = -1.75

Simplifying
n = -1.75
Subproblem 2
Set the factor '(1 + -1n)' equal to zero and attempt to solve:

Simplifying
1 + -1n = 0

Solving
1 + -1n = 0

Move all terms containing n to the left, all other terms to the right.

Add '-1' to each side of the equation.
1 + -1 + -1n = 0 + -1

Combine like terms: 1 + -1 = 0
0 + -1n = 0 + -1
-1n = 0 + -1

Combine like terms: 0 + -1 = -1
-1n = -1

Divide each side by '-1'.
n = 1

Simplifying
n = 1
Solution
n = {-1.75, 1}