3. A company's annual revenue after x years is f (x) = x3 - 9x2 + 15x + 29 thousand dollars (forx 2 0). (a) Make a sign diagram for the first derivative. Show how you are obtaining the sign of the first derivative. (b) Make a sign diagram for the second derivative. Show how you are obtaining the sign of the second derivative. (c) Sketch the graph of the revenue function, showing all relative extreme points and inflection points. (d) Interpret the inflection point