There are 1 questions in this calculation: for each question, the 1 derivative of x is calculated.
    Note that variables are case sensitive.
\[ \begin{equation}\begin{split}[1/1]Find\ the\ first\ derivative\ of\ function\ (80 - x - 50)(200 + 20x)\ with\ respect\ to\ x：\\\end{split}\end{equation} \]\[ \begin{equation}\begin{split}\\Solution:&\\ &Primitive\ function\ = 400x - 20x^{2} + 6000\\&\color{blue}{The\ first\ derivative\ function：}\\&\frac{d\left( 400x - 20x^{2} + 6000\right)}{dx}\\=&400 - 20*2x + 0\\=& - 40x + 400\\ \end{split}\end{equation} \]

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