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

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