# Calculus: Other Calculus Problems – #441

Question: Suppose that when it is $$t$$ years old a particular industrial machine generates revenue at the rate $$R'(t)=6,025-8{{t}^{2}}$$ dollars per year, and that operating and servicing costs accumulate a the rate of $$C'(t)=4,681+13{{t}^{2}}$$ dollars per year

(a) How many years pass before the profitability of the machine begins to decline?

(b) What are the net earnings?

(c) Show a graph