How can i find the second derivative of this function?
$\displaystyle (-3x^2)/(3y^2) $
i suppose you want to differentiate with respect to x, that is, to find dy/dx?
just differentiate regularly, using the quotient or product rule. when you differentiate a y-term, attach "dy/dx" to it, to say, you "differentiated a y-term with respect to x." similarly, when you differentiate the x-term, you would attach dx/dx, but you don't write it, because that is just 1
try it, what do you get?