r(r-12)=3r

Solution for r(r-12)=3r equation:

Simplifying
r(r + -12) = 3r

Reorder the terms:
r(-12 + r) = 3r
(-12 * r + r * r) = 3r
(-12r + r2) = 3r

Solving
-12r + r2 = 3r

Solving for variable 'r'.

Reorder the terms:
-12r + -3r + r2 = 3r + -3r

Combine like terms: -12r + -3r = -15r
-15r + r2 = 3r + -3r

Combine like terms: 3r + -3r = 0
-15r + r2 = 0

Factor out the Greatest Common Factor (GCF), 'r'.
r(-15 + r) = 0

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 '(-15 + r)' equal to zero and attempt to solve:

Simplifying
-15 + r = 0

Solving
-15 + r = 0

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

Add '15' to each side of the equation.
-15 + 15 + r = 0 + 15

Combine like terms: -15 + 15 = 0
0 + r = 0 + 15
r = 0 + 15

Combine like terms: 0 + 15 = 15
r = 15

Simplifying
r = 15
Solution
r = {0, 15}