There are 1 questions in this calculation: for each question, the 2 derivative of x is calculated.
    Note that variables are case sensitive.
\[ \begin{equation}\begin{split}[1/1]Find\ the\ second\ derivative\ of\ function\ (\frac{21}{2}{x}^{3} + 7290{x}^{2} + \frac{87480x}{(2160 + 8x)})\ with\ respect\ to\ x：\\\end{split}\end{equation} \]\[ \begin{equation}\begin{split}\\Solution:&\\ &Primitive\ function\ = \frac{21}{2}x^{3} + 7290x^{2} + \frac{87480x}{(8x + 2160)}\\&\color{blue}{The\ first\ derivative\ function：}\\&\frac{d\left( \frac{21}{2}x^{3} + 7290x^{2} + \frac{87480x}{(8x + 2160)}\right)}{dx}\\=&\frac{21}{2}*3x^{2} + 7290*2x + 87480(\frac{-(8 + 0)}{(8x + 2160)^{2}})x + \frac{87480}{(8x + 2160)}\\=&\frac{63x^{2}}{2} + 14580x - \frac{699840x}{(8x + 2160)^{2}} + \frac{87480}{(8x + 2160)}\\\\ &\color{blue}{The\ second\ derivative\ of\ function:} \\&\frac{d\left( \frac{63x^{2}}{2} + 14580x - \frac{699840x}{(8x + 2160)^{2}} + \frac{87480}{(8x + 2160)}\right)}{dx}\\=&\frac{63*2x}{2} + 14580 - 699840(\frac{-2(8 + 0)}{(8x + 2160)^{3}})x - \frac{699840}{(8x + 2160)^{2}} + 87480(\frac{-(8 + 0)}{(8x + 2160)^{2}})\\=&63x + \frac{11197440x}{(8x + 2160)^{3}} - \frac{1399680}{(8x + 2160)^{2}} + 14580\\ \end{split}\end{equation} \]

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