Answer:
r = 0, r = 12
Step-by-step explanation:
9[tex]r^{2}[/tex]=108r
Subtract 108r from both sides
9[tex]r^{2}[/tex] - 108r = 108r - 108r (simplify) -> 9[tex]r^{2}[/tex] - 108r = 0
Factor 9[tex]r^{2}[/tex] - 108r: 9[tex]r^{2}[/tex] (r - 12)
9[tex]r^{2}[/tex] (r - 12) = 0
r = 0, r = 12
