21k^2-36k+15=0

Solution for 21k^2-36k+15=0 equation:

Simplifying
21k2 + -36k + 15 = 0

Reorder the terms:
15 + -36k + 21k2 = 0

Solving
15 + -36k + 21k2 = 0

Solving for variable 'k'.

Factor out the Greatest Common Factor (GCF), '3'.
3(5 + -12k + 7k2) = 0

Factor a trinomial.
3((5 + -7k)(1 + -1k)) = 0

Ignore the factor 3.
Subproblem 1
Set the factor '(5 + -7k)' equal to zero and attempt to solve:

Simplifying
5 + -7k = 0

Solving
5 + -7k = 0

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

Add '-5' to each side of the equation.
5 + -5 + -7k = 0 + -5

Combine like terms: 5 + -5 = 0
0 + -7k = 0 + -5
-7k = 0 + -5

Combine like terms: 0 + -5 = -5
-7k = -5

Divide each side by '-7'.
k = 0.7142857143

Simplifying
k = 0.7142857143
Subproblem 2
Set the factor '(1 + -1k)' equal to zero and attempt to solve:

Simplifying
1 + -1k = 0

Solving
1 + -1k = 0

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

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

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

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

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

Simplifying
k = 1
Solution
k = {0.7142857143, 1}