I was asked to differentiate $((1-3x)^5-x^2)^4$ with respect to x, I thought that I would have to apply chain rule to the internal function before moving on to the outside. However, the answer was $-4((1-3x)^5-x^2)^3(15(1-3x)^4+2x)$. How was this achieved so simply?
The answer is most probably wrong.
The common method to do this type of problems is by applying the chain rule.
Let,$y=[(1-3x)^5-x^2]^4$ and let,$z=(1-3x)^5-x^2$
Now,you can continue as usual.(Don't forget to substitute the $z$ at last).