There are 1 questions in this calculation: for each question, the 1 derivative of x is calculated.
    Note that variables are case sensitive.
\[ \begin{equation}\begin{split}[1/1]Find\ the\ first\ derivative\ of\ function\ ({r}^{2} + (2r + R)x){\frac{1}{(r + x)}}^{2}\ with\ respect\ to\ x：\\\end{split}\end{equation} \]\[ \begin{equation}\begin{split}\\Solution:&\\ &Primitive\ function\ = \frac{2rx}{(r + x)^{2}} + \frac{r^{2}}{(r + x)^{2}} + \frac{Rx}{(r + x)^{2}}\\&\color{blue}{The\ first\ derivative\ function：}\\&\frac{d\left( \frac{2rx}{(r + x)^{2}} + \frac{r^{2}}{(r + x)^{2}} + \frac{Rx}{(r + x)^{2}}\right)}{dx}\\=&2(\frac{-2(0 + 1)}{(r + x)^{3}})rx + \frac{2r}{(r + x)^{2}} + (\frac{-2(0 + 1)}{(r + x)^{3}})r^{2} + 0 + (\frac{-2(0 + 1)}{(r + x)^{3}})Rx + \frac{R}{(r + x)^{2}}\\=&\frac{-4rx}{(r + x)^{3}} + \frac{2r}{(r + x)^{2}} - \frac{2r^{2}}{(r + x)^{3}} - \frac{2Rx}{(r + x)^{3}} + \frac{R}{(r + x)^{2}}\\ \end{split}\end{equation} \]

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