21r^2=3r

Solution for 21r^2=3r equation:

Simplifying
21r2 = 3r

Solving
21r2 = 3r

Solving for variable 'r'.

Reorder the terms:
-3r + 21r2 = 3r + -3r

Combine like terms: 3r + -3r = 0
-3r + 21r2 = 0

Factor out the Greatest Common Factor (GCF), '3r'.
3r(-1 + 7r) = 0

Ignore the factor 3.
Subproblem 1
Set the factor 'r' equal to zero and attempt to solve:

Simplifying
r = 0

Solving
r = 0

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

Simplifying
r = 0
Subproblem 2
Set the factor '(-1 + 7r)' equal to zero and attempt to solve:

Simplifying
-1 + 7r = 0

Solving
-1 + 7r = 0

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

Add '1' to each side of the equation.
-1 + 1 + 7r = 0 + 1

Combine like terms: -1 + 1 = 0
0 + 7r = 0 + 1
7r = 0 + 1

Combine like terms: 0 + 1 = 1
7r = 1

Divide each side by '7'.
r = 0.1428571429

Simplifying
r = 0.1428571429
Solution
r = {0, 0.1428571429}