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

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