There are 1 questions in this calculation: for each question, the 2 derivative of x is calculated.
    Note that variables are case sensitive.
\[ \begin{equation}\begin{split}[1/1]Find\ the\ second\ derivative\ of\ function\ \frac{x}{sqrt({d}^{2} + {x}^{2})}\ with\ respect\ to\ x：\\\end{split}\end{equation} \]\[ \begin{equation}\begin{split}\\Solution:&\\ &Primitive\ function\ = \frac{x}{sqrt(d^{2} + x^{2})}\\&\color{blue}{The\ first\ derivative\ function：}\\&\frac{d\left( \frac{x}{sqrt(d^{2} + x^{2})}\right)}{dx}\\=&\frac{1}{sqrt(d^{2} + x^{2})} + \frac{x*-(0 + 2x)*\frac{1}{2}}{(d^{2} + x^{2})(d^{2} + x^{2})^{\frac{1}{2}}}\\=&\frac{1}{sqrt(d^{2} + x^{2})} - \frac{x^{2}}{(d^{2} + x^{2})^{\frac{3}{2}}}\\\\ &\color{blue}{The\ second\ derivative\ of\ function:} \\&\frac{d\left( \frac{1}{sqrt(d^{2} + x^{2})} - \frac{x^{2}}{(d^{2} + x^{2})^{\frac{3}{2}}}\right)}{dx}\\=&\frac{-(0 + 2x)*\frac{1}{2}}{(d^{2} + x^{2})(d^{2} + x^{2})^{\frac{1}{2}}} - (\frac{\frac{-3}{2}(0 + 2x)}{(d^{2} + x^{2})^{\frac{5}{2}}})x^{2} - \frac{2x}{(d^{2} + x^{2})^{\frac{3}{2}}}\\=&\frac{-3x}{(d^{2} + x^{2})^{\frac{3}{2}}} + \frac{3x^{3}}{(d^{2} + x^{2})^{\frac{5}{2}}}\\ \end{split}\end{equation} \]

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