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

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