21c^2+4c-12=0

Solution for 21c^2+4c-12=0 equation:

Simplifying
21c2 + 4c + -12 = 0

Reorder the terms:
-12 + 4c + 21c2 = 0

Solving
-12 + 4c + 21c2 = 0

Solving for variable 'c'.

Factor a trinomial.
(-6 + -7c)(2 + -3c) = 0

Subproblem 1
Set the factor '(-6 + -7c)' equal to zero and attempt to solve:

Simplifying
-6 + -7c = 0

Solving
-6 + -7c = 0

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

Add '6' to each side of the equation.
-6 + 6 + -7c = 0 + 6

Combine like terms: -6 + 6 = 0
0 + -7c = 0 + 6
-7c = 0 + 6

Combine like terms: 0 + 6 = 6
-7c = 6

Divide each side by '-7'.
c = -0.8571428571

Simplifying
c = -0.8571428571
Subproblem 2
Set the factor '(2 + -3c)' equal to zero and attempt to solve:

Simplifying
2 + -3c = 0

Solving
2 + -3c = 0

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

Add '-2' to each side of the equation.
2 + -2 + -3c = 0 + -2

Combine like terms: 2 + -2 = 0
0 + -3c = 0 + -2
-3c = 0 + -2

Combine like terms: 0 + -2 = -2
-3c = -2

Divide each side by '-3'.
c = 0.6666666667

Simplifying
c = 0.6666666667
Solution
c = {-0.8571428571, 0.6666666667}