There are 1 questions in this calculation: for each question, the 1 derivative of x is calculated.
    Note that variables are case sensitive.
\[ \begin{equation}\begin{split}[1/1]Find\ the\ first\ derivative\ of\ function\ {cos(7x)}^{2}\ with\ respect\ to\ x：\\\end{split}\end{equation} \]\[ \begin{equation}\begin{split}\\Solution:&\\ &Primitive\ function\ = cos^{2}(7x)\\&\color{blue}{The\ first\ derivative\ function：}\\&\frac{d\left( cos^{2}(7x)\right)}{dx}\\=&-2cos(7x)sin(7x)*7\\=&-14sin(7x)cos(7x)\\ \end{split}\end{equation} \]

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