There are 1 questions in this calculation: for each question, the 1 derivative of y is calculated.
    Note that variables are case sensitive.
\[ \begin{equation}\begin{split}[1/1]Find\ the\ first\ derivative\ of\ function\ {y}^{-2}cos(\frac{x}{y})\ with\ respect\ to\ y：\\\end{split}\end{equation} \]\[ \begin{equation}\begin{split}\\Solution:&\\ &Primitive\ function\ = \frac{cos(\frac{x}{y})}{y^{2}}\\&\color{blue}{The\ first\ derivative\ function：}\\&\frac{d\left( \frac{cos(\frac{x}{y})}{y^{2}}\right)}{dy}\\=&\frac{-2cos(\frac{x}{y})}{y^{3}} + \frac{-sin(\frac{x}{y})x*-1}{y^{2}y^{2}}\\=&\frac{-2cos(\frac{x}{y})}{y^{3}} + \frac{xsin(\frac{x}{y})}{y^{4}}\\ \end{split}\end{equation} \]

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