Problem 1257 (difficulty: 5/10)

Let \(\displaystyle B\) be a real \(\displaystyle q\times r\) matrix. What is the derivative of

\(\displaystyle f(x_1,\ldots,x_{q+r}) = (x_1,\ldots,x_q)M(x_{q+1},\ldots,x_{q+r})^T?\)

Answer-->

Give me another random problem!