3k^2-18-21=0

Solution for 3k^2-18-21=0 equation:

Simplifying
3k2 + -18 + -21 = 0

Reorder the terms:
-18 + -21 + 3k2 = 0

Combine like terms: -18 + -21 = -39
-39 + 3k2 = 0

Solving
-39 + 3k2 = 0

Solving for variable 'k'.

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

Add '39' to each side of the equation.
-39 + 39 + 3k2 = 0 + 39

Combine like terms: -39 + 39 = 0
0 + 3k2 = 0 + 39
3k2 = 0 + 39

Combine like terms: 0 + 39 = 39
3k2 = 39

Divide each side by '3'.
k2 = 13

Simplifying
k2 = 13

Take the square root of each side:
k = {-3.605551275, 3.605551275}