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

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