The surface is shown in the diagram.
The green point is and the red point
is .
(a) Are the following quantities positive, negative, or zero?
1.
2.
3.
4.
5.
6.
7.
8.
(b) Suppose a point in the xy-plane moves in a straight line
from the green point to the red point
.
1. Does the sign of change from nonnegative to negative, nonpositive to positive, or is there no change in sign?
2. Does the sign of change from nonnegative to negative, nonpositive to positive, or is there no change in sign?
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