$\displaystyle 3x^2\ln(1-xy)$
i want to differentiate with respect to y.
So.
$\displaystyle [(0)(\ln(1-xy)]+[(3x^2)(-x)]$
which is $\displaystyle -3x^3$
Is that correct?
Just treat $\displaystyle x$ like a number. $\displaystyle 3x^2$ and $\displaystyle x$ are just constants.
If you were derivating $\displaystyle c_1\ln(1-c_2 y)$, what would you get? You'd get $\displaystyle \frac{c_1}{1-c_2 y}\cdot -c_2$. Just extend that notion to this problem.