Question 748235
r^3=2r^2+15r
r^3 - 2r^2 - 15r = 0
r(r^2 - 2r - 15) = 0

Therefore r = 0, is one solution and whenever (r^2 - 2r - 15) = 0, the equation is satisfied.

r^2 - 2r - 15 = 0
(r-5)(r+3) = 0

Therefore, r = 5 and r = -3 are also solutions.

Finally, r = 0, r = -3, and r = 5 are the solutions to the original equation.