Question

Quick question about 3d graphs and the 2nd derivative test. Is f_xx supposed to be negative at the point of a local max?

Answer 1

For instance the attached image has a local max at the red dot. It'd be correct to say that the 2nd partial derivative with respect to x would be neg, right?

Answer 2

@jigglypuff314 halp =)

Answer 3

@zepdrix ^^

Answer 4

@johnweldon1993 @Compassionate

Answer 5

Correct, a negative result from the second derivative test would correspond to a concave DOWN situation