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

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