WeBWorK Standalone Renderer

The contour plot of $z = f(x,y)$ is shown below. Determine if the given quantity in each part is positive, negative, or zero.

1. The value of $\nabla f \cdot \vec{j}$ at the point $P = (-4,2)$ .

2. The value of $\nabla f \cdot \vec{i}$ at the point $P = (-4,2)$ .

3. $\displaystyle \frac{\partial f}{\partial x}$ at the point $Q = (1,-1)$ .

4. $\displaystyle \frac{\partial f}{\partial y}$ at the point $Q = (1,-1)$ .

(Click on graph to enlarge)

In order to get credit for this problem all answers must be correct.