There are 1 questions in this calculation: for each question, the 1 derivative of x is calculated.
    Note that variables are case sensitive.
\[ \begin{equation}\begin{split}[1/1]Find\ the\ first\ derivative\ of\ function\ \frac{3sin(X)}{(1 + cos(X))}\ with\ respect\ to\ x：\\\end{split}\end{equation} \]\[ \begin{equation}\begin{split}\\Solution:&\\ &Primitive\ function\ = \frac{3sin(X)}{(cos(X) + 1)}\\&\color{blue}{The\ first\ derivative\ function：}\\&\frac{d\left( \frac{3sin(X)}{(cos(X) + 1)}\right)}{dx}\\=&3(\frac{-(-sin(X)*0 + 0)}{(cos(X) + 1)^{2}})sin(X) + \frac{3cos(X)*0}{(cos(X) + 1)}\\=&0\\ \end{split}\end{equation} \]

Your problem has not been solved here? Please take a look at the  hot problems ！