Hello I'm trying to do some research on polynomial expansion however my math isn't that good to do high level calculations, proofs and so on. A while ago my friend came up with a formula for finding number of terms in any expansion of a polynomial to the y power. For example for (a+b+c+d)^4 = 35 terms Formula: n-y-1Cy for n = number of terms in paranthases. Can anyone help me, give some clues on how to proof this formula or show me a proof? Thanks!