**Question: **Suppose that when its \(x\) years old, an industrial machine generates revenue at the rate of \(R(x)=5920-12{{x}^{2}}\) per year, and results in costs that accumulate at the rate of \(C(x)=4000+18{{x}^{2}}\)

a) For how many years is the use of the machine profitable?

b) Find the net earnings generated by the machine during the time it’s profitable.