It's now been 2 decades since I studied functions and calculaus in high school. I'm sure 75% of it will come back to me fairly quickly, but it seems to be written in a way that makes no sense to me. This is what I'm studying: http://ocw.mit.edu/ans7870/resources/Strang/Edited/Calculus/1.pdf [Broken] I'm in the exercises portion on p.7. My answers are bolded 1.1 Exercises Starting from f(0) = 0 at constant velocity v, the distance function is f (t)= v.t . When f (t) = 55t the velocity is v = v . When f(t) = 55t + 1000 the velocity is still v and the starting value is f (0)= 1000 . In each case v is the slope of the graph of f. When v is negative, the graphof f(t) goes downward. In that case area in the t.-graph counts as absolute value (?). Forward motion from f (0)= 0 to f (2)= 10 has v = 5 . Then backward motion to f (4)= 0 has v = ? . Did I get them right? I'm not sure about the second last one. What is really confusing me is that this doesn't seem to be the way I learned it in H.S. The answers were very difficult for me to get. We always started with the formulae. I don't see any formula above - though I guess I've gotten the answers so far. But on that last one, how am I supposed to know what f(4) is if I don't even know what the formula is? This is not grokking.