I was wondering if someone could give me a hand here with 2b) on the following link. http://www.am.qub.ac.uk/users/j.mccann/teaching/ama102/2003/assignments/assign_8.pdf For part a) I got it to be equal to 3x^2+3y^2+3z^2+2y-2xy, and I'm hoping that's right! However, for part b) I can't seem to get the answer they're after at all. We haven't covered any examples of this in our lectures yet and we won't have any lectures before the homework has to be handed in due to May Day, so any help would be much appreciated. Just to make sure I started it off right, could you just check if this is correct or not (sorry, I'm no good with LaTex!)- triple integral of (3r^2sin^2(theta)cos^2(f)+ 3r^2sin^3(theta)sin^2(f) + 3r^2cos^2(theta) + 2rsin(theta)sin(f) - 2r^2sin^2(theta)cos(f)sin)f))r^2sin(theta)drdfdtheta where the integral with respect to r is within the limits 0 and a, with respect to f is 0 to 2pi and with respect to theta is 0 to pi (where f is the asimuthal angle or whatever it's called). I'd really appreciate if you could just ehck I've done that bit okay, because it'd be a bit pointless me running through it if the mistake was in the first line. Btw, the answer I get at the end has an 8 on the numerator instead of a 12, so the answer isn't completely far out so I'm hoping it's just a wee mistake somewhere. Thanks! Btw, sorry if this is posted in the wrong forum!