There are 1 questions in this calculation: for each question, the 2 derivative of x is calculated.
    Note that variables are case sensitive.
\[ \begin{equation}\begin{split}[1/1]Find\ the\ second\ derivative\ of\ function\ 3x - \frac{cos(9x)}{9} + ln(16)\ with\ respect\ to\ x：\\\end{split}\end{equation} \]\[ \begin{equation}\begin{split}\\Solution:&\\ &\color{blue}{The\ first\ derivative\ function：}\\&\frac{d\left( 3x - \frac{1}{9}cos(9x) + ln(16)\right)}{dx}\\=&3 - \frac{1}{9}*-sin(9x)*9 + \frac{0}{(16)}\\=&sin(9x) + 3\\\\ &\color{blue}{The\ second\ derivative\ of\ function:} \\&\frac{d\left( sin(9x) + 3\right)}{dx}\\=&cos(9x)*9 + 0\\=&9cos(9x)\\ \end{split}\end{equation} \]

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