1. The problem statement, all variables and given/known data 2. Relevant equations Y=1/2*(X1-X3)^2+1/14*(X2+2X4-3X5)^2 3. The attempt at a solution For (a) part, I have only learnt to find the moment-generating function of Y, but not finding the p.d.f. Moreover, the examples I have seen only involves random variables Xi to the power 1, but not to higher power. For (b) part, the difficulty for me is just similar to part (a).