*Question 1a* We have $\begin{align} f_{x} &= 2x+ 5xy &f_{y}&= 5x + 12y^3 \\ f_{xx} &= 2+5y &f_{yy} &= 36y^2 \\ f_{xy}&=5 =f_{yx} \end{align}$ *Question 1b* The gradient of $f$ is given by $\nabla f = (f_{x},f_{y})$and $fs divergence is given by $\nabla \cdot f = f_{x}+f_{y}$