There are 1 questions in this calculation: for each question, the 2 derivative of x is calculated.
    Note that variables are case sensitive.
\[ \begin{equation}\begin{split}[1/1]Find\ the\ second\ derivative\ of\ function\ \frac{(y - x)}{(x + 20)}\ with\ respect\ to\ x：\\\end{split}\end{equation} \]\[ \begin{equation}\begin{split}\\Solution:&\\ &Primitive\ function\ = \frac{y}{(x + 20)} - \frac{x}{(x + 20)}\\&\color{blue}{The\ first\ derivative\ function：}\\&\frac{d\left( \frac{y}{(x + 20)} - \frac{x}{(x + 20)}\right)}{dx}\\=&(\frac{-(1 + 0)}{(x + 20)^{2}})y + 0 - (\frac{-(1 + 0)}{(x + 20)^{2}})x - \frac{1}{(x + 20)}\\=&\frac{-y}{(x + 20)^{2}} + \frac{x}{(x + 20)^{2}} - \frac{1}{(x + 20)}\\\\ &\color{blue}{The\ second\ derivative\ of\ function:} \\&\frac{d\left( \frac{-y}{(x + 20)^{2}} + \frac{x}{(x + 20)^{2}} - \frac{1}{(x + 20)}\right)}{dx}\\=&-(\frac{-2(1 + 0)}{(x + 20)^{3}})y + 0 + (\frac{-2(1 + 0)}{(x + 20)^{3}})x + \frac{1}{(x + 20)^{2}} - (\frac{-(1 + 0)}{(x + 20)^{2}})\\=&\frac{2y}{(x + 20)^{3}} - \frac{2x}{(x + 20)^{3}} + \frac{2}{(x + 20)^{2}}\\ \end{split}\end{equation} \]

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