1. The problem statement, all variables and given/known data A exp( (− 3 R^2)/(2Na^2)) I wish to integrate ^ The expression is equal to P(N,R) The limits are infinity to -infinity. The intention is to find the normalisation constant / A in terms of N and a (then to cube it). 3. The attempt at a solution This is what I've managed. A S e^(-3R^2) dR + S e^(0.5Na^2) dN (S being integral) Am I on the right tracks? Should I separate e^0.5 and integrate with respect to N, or should I not integrate it? Thank you everyone who's helped me along so far.