There are 1 questions in this calculation: for each question, the 3 derivative of x is calculated.
    Note that variables are case sensitive.
\[ \begin{equation}\begin{split}[1/1]Find\ the\ third\ derivative\ of\ function\ A{x}^{2}e^{-x}\ with\ respect\ to\ x：\\\end{split}\end{equation} \]\[ \begin{equation}\begin{split}\\Solution:&\\ &Primitive\ function\ = Ax^{2}e^{-x}\\&\color{blue}{The\ first\ derivative\ function：}\\&\frac{d\left( Ax^{2}e^{-x}\right)}{dx}\\=&A*2xe^{-x} + Ax^{2}e^{-x}*-1\\=&2Axe^{-x} - Ax^{2}e^{-x}\\\\ &\color{blue}{The\ second\ derivative\ of\ function:} \\&\frac{d\left( 2Axe^{-x} - Ax^{2}e^{-x}\right)}{dx}\\=&2Ae^{-x} + 2Axe^{-x}*-1 - A*2xe^{-x} - Ax^{2}e^{-x}*-1\\=&2Ae^{-x} - 4Axe^{-x} + Ax^{2}e^{-x}\\\\ &\color{blue}{The\ third\ derivative\ of\ function:} \\&\frac{d\left( 2Ae^{-x} - 4Axe^{-x} + Ax^{2}e^{-x}\right)}{dx}\\=&2Ae^{-x}*-1 - 4Ae^{-x} - 4Axe^{-x}*-1 + A*2xe^{-x} + Ax^{2}e^{-x}*-1\\=&-6Ae^{-x} + 6Axe^{-x} - Ax^{2}e^{-x}\\ \end{split}\end{equation} \]

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