I am trying to figure out the derivative of $y= \frac{t\sin t}{1+t}$ I know the quotient rules are needed but I think what is confusing is some fairly simple math. Here is what I did.
(1+t)(tcost) - (tsint)(1) this could be wrong but I think it is correct. Anyways what I was confused on was multiplying t into tcost. I forget the rules but is tcost times t should be $t^2\cos$ or something close but I am not sure. Anyways I end up with $ \frac{t\cos t+t^2 \cos t - t \sin t}{(1+t)^2}$ but this is not correct.