Calculus I Sample Exam Sample Answers (with a few hints)

Note: These are not meant to be complete answers as you would complete them on the exam itself; rather, they are to be used as a guide towards correct solutions.





  1. The cubic has three roots; by hunting a lot we see that they're around x=1, x=-8, x=116 (very roughly!) We see that 2^x crosses this graph twice near the two roots: at x = -8.563 (to three decimal places) and at x = 1 (exactly, I think.). After that 2^x starts climbing very quickly, and the cubic becomes negative until x is about 116. By this time 2^x is about 10^35. Since exponential functions dominate cubics eventually, we can safely conclude that the cubic function will never catch up, and we've found the only two solutions.


  2. I tried to sketch the graph so that when the was narrow, the height was going up quickly, when the the vase was wide, the height was going up slowly, and when the vase was of roughly constant height, the height was going up at a constant rate. One such graph might be:


  3. The equation of the parabola is y = -(x-2)(x+2). Then the coordinates of the two points are (1.75, 0.9375) and (-sqrt(3.25),0.75). Then an equation of the line is y - 0.9375 = (0.1875/(1.75+\sqrt(3.25))(x-1.75).