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

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