There are 1 questions in this calculation: for each question, the 4 derivative of x is calculated.
    Note that variables are case sensitive.
\[ \begin{equation}\begin{split}[1/1]Find\ the\ 4th\ derivative\ of\ function\ cos(3x)\ with\ respect\ to\ x：\\\end{split}\end{equation} \]\[ \begin{equation}\begin{split}\\Solution:&\\ &\color{blue}{The\ first\ derivative\ function：}\\&\frac{d\left( cos(3x)\right)}{dx}\\=&-sin(3x)*3\\=&-3sin(3x)\\\\ &\color{blue}{The\ second\ derivative\ of\ function:} \\&\frac{d\left( -3sin(3x)\right)}{dx}\\=&-3cos(3x)*3\\=&-9cos(3x)\\\\ &\color{blue}{The\ third\ derivative\ of\ function:} \\&\frac{d\left( -9cos(3x)\right)}{dx}\\=&-9*-sin(3x)*3\\=&27sin(3x)\\\\ &\color{blue}{The\ 4th\ derivative\ of\ function:} \\&\frac{d\left( 27sin(3x)\right)}{dx}\\=&27cos(3x)*3\\=&81cos(3x)\\ \end{split}\end{equation} \]

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