00:01
In this question, they give us a contour map for a function f of x, y.
00:04
And we want to determine the signs of the following partial derivatives at the given points.
00:11
First, i want the partial derivative of f with respect to x at point a.
00:17
So what is the question being asked? we're being asked, if i go to point a, if i were to travel in the direction of the positive x -axis, would the z values on my function be increasing or decreasing? now, the point a appears to be on the contour labeled 30.
00:43
If i move directly to the right, my z values are increasing towards the contours that are marked as 50 and 70.
00:53
And so therefore, my z is increasing as i move in the x direction, which means my partial derivative is positive.
01:02
The partial of f with respect to x at point a is greater than zero...