Hey! I'm a complete newbie to integral calculus (and well, to math in general - but I'm trying to learn!) and I have a bit of a problem. I already get the feeling that the solution is ridiculously simple, but my brain just isn't making the connection. 1. The problem statement, all variables and given/known data Given are two functions: f(x) = 2x√x and g(x) = -2x + 24 that intersect at points (4, 16) Problem: Calculate the center of gravity bounded by the two axes and graph of g(x). 2. Relevant equations The teacher's solution gives the equation A: 1/2 * 12 * 24 = 144 and the integral boundaries are defined from 0 to 12. 3. The attempt at a solution Well, the answer is known but my problem is that I can't figure out how it got there. I do know that if an area is bounded by a graph of a function and an axis, then one of the boundaries is set at 0... But I feel that I'm missing something very basic (which wouldn't surprise me, since my math education until now is pretty, uh, bad.) I guess the problem is that I don't know how to actually *think* about the problem, I'm just aimlessly playing around with the numbers (16 - 4 makes 12! x is 12! Is that the boundary? Why? I don't know!) If you could kick me in the right direction I would appreciate it a lot! ^^ Thank you.