There are 1 questions in this calculation: for each question, the 1 derivative of x is calculated.
    Note that variables are case sensitive.
\[ \begin{equation}\begin{split}[1/1]Find\ the\ first\ derivative\ of\ function\ 3{x}^{2} + xcos(x)\ with\ respect\ to\ x：\\\end{split}\end{equation} \]\[ \begin{equation}\begin{split}\\Solution:&\\ &Primitive\ function\ = xcos(x) + 3x^{2}\\&\color{blue}{The\ first\ derivative\ function：}\\&\frac{d\left( xcos(x) + 3x^{2}\right)}{dx}\\=&cos(x) + x*-sin(x) + 3*2x\\=&cos(x) - xsin(x) + 6x\\ \end{split}\end{equation} \]

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