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

Your problem has not been solved here? Please take a look at the  hot problems ！