There are 1 questions in this calculation: for each question, the 2 derivative of x is calculated.
    Note that variables are case sensitive.
\[ \begin{equation}\begin{split}[1/1]Find\ the\ second\ derivative\ of\ function\ \frac{1}{({x}^{2} + {a}^{2})}\ with\ respect\ to\ x：\\\end{split}\end{equation} \]\[ \begin{equation}\begin{split}\\Solution:&\\ &Primitive\ function\ = \frac{1}{(x^{2} + a^{2})}\\&\color{blue}{The\ first\ derivative\ function：}\\&\frac{d\left( \frac{1}{(x^{2} + a^{2})}\right)}{dx}\\=&(\frac{-(2x + 0)}{(x^{2} + a^{2})^{2}})\\=&\frac{-2x}{(x^{2} + a^{2})^{2}}\\\\ &\color{blue}{The\ second\ derivative\ of\ function:} \\&\frac{d\left( \frac{-2x}{(x^{2} + a^{2})^{2}}\right)}{dx}\\=&-2(\frac{-2(2x + 0)}{(x^{2} + a^{2})^{3}})x - \frac{2}{(x^{2} + a^{2})^{2}}\\=&\frac{8x^{2}}{(x^{2} + a^{2})^{3}} - \frac{2}{(x^{2} + a^{2})^{2}}\\ \end{split}\end{equation} \]

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