1. The problem statement, all variables and given/known data n=y*sqrt((V)/(v*x) and Q=sqrt(v*V*x)*f(n) so i have V=-dQ/dx=(dQ/dn)*(dn/dx) and the final answer is V=(1/2)*sqrt((v*V)/x)(n*df/dn-f) 2. Relevant equations 3. The attempt at a solution i have tried diff. by hand and also by maple and cannot get the answer. What am i doing wrong, because after all i have to quantities added together and that seems weird to me.