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

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