There are 1 questions in this calculation: for each question, the 2 derivative of x is calculated.
    Note that variables are case sensitive.
\[ \begin{equation}\begin{split}[1/1]Find\ the\ second\ derivative\ of\ function\ \frac{\frac{21}{2}}{(cos(x)tan(2x))}\ with\ respect\ to\ x：\\\end{split}\end{equation} \]\[ \begin{equation}\begin{split}\\Solution:&\\ &Primitive\ function\ = \frac{\frac{21}{2}}{cos(x)tan(2x)}\\&\color{blue}{The\ first\ derivative\ function：}\\&\frac{d\left( \frac{\frac{21}{2}}{cos(x)tan(2x)}\right)}{dx}\\=&\frac{\frac{21}{2}sin(x)}{cos^{2}(x)tan(2x)} + \frac{\frac{21}{2}*-sec^{2}(2x)(2)}{cos(x)tan^{2}(2x)}\\=&\frac{21sin(x)}{2cos^{2}(x)tan(2x)} - \frac{21sec^{2}(2x)}{cos(x)tan^{2}(2x)}\\\\ &\color{blue}{The\ second\ derivative\ of\ function:} \\&\frac{d\left( \frac{21sin(x)}{2cos^{2}(x)tan(2x)} - \frac{21sec^{2}(2x)}{cos(x)tan^{2}(2x)}\right)}{dx}\\=&\frac{21cos(x)}{2cos^{2}(x)tan(2x)} + \frac{21sin(x)*2sin(x)}{2cos^{3}(x)tan(2x)} + \frac{21sin(x)*-sec^{2}(2x)(2)}{2cos^{2}(x)tan^{2}(2x)} - \frac{21sin(x)sec^{2}(2x)}{cos^{2}(x)tan^{2}(2x)} - \frac{21*-2sec^{2}(2x)(2)sec^{2}(2x)}{cos(x)tan^{3}(2x)} - \frac{21*2sec^{2}(2x)tan(2x)*2}{cos(x)tan^{2}(2x)}\\=&\frac{84sec^{4}(2x)}{cos(x)tan^{3}(2x)} - \frac{42sin(x)sec^{2}(2x)}{cos^{2}(x)tan^{2}(2x)} + \frac{21sin^{2}(x)}{cos^{3}(x)tan(2x)} - \frac{84sec^{2}(2x)}{cos(x)tan(2x)} + \frac{21}{2cos(x)tan(2x)}\\ \end{split}\end{equation} \]

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