This is the quantum part for solving wavefunctions of mulit-electron atoms that need to be approximated by the variation method. Specifically we are supposed to differentiate this equation using the quotient rule : E(c1,c2) = [(c1^2*H11 + 2c1c2H12 + c2^2*H22) / (c1^2*S11 + 2c1c2*S12 + c2^2S22)] Our book only shows the way to do it using the product rule after you bring the bottom onto the initial left side of the equation... H and S are constants, with c as the adjustable variable of the equation... I think. I've finished the differentiation but I got a different answer than I should have (we were given the answer)... Could anyone refer me to a website or something that shows the quotient rule? Thanks in advance!