9. (a) Find the equation of the tangent line to the graph of the function f (x) = x3 + x2 + x at the point (1, 3). (b) Use your result in (a) to give a linear approximation for f(1.1) . 10. The value ($) of a stock t months from the beginning of a 24-month period was found to be modeled by V(t) = 100 + 0.3t2 - 0.01t3, (0 S t