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

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