S.O.S. Mathematics CyberBoard

this is a previous exam all the answers are given i would just like to know how or simply why is it that answer. thanks
#1 is cob douglas function
1) Q= 6k^(1/6)L^(5/6). Then
answer: dK/dL= -5K/L ??
2)Suppose utility is strictly concave. Then
answer: average utility is greater than marginal utility ??
3) f is a differentiable univariate function. Then
a. a stationary point is necessary for a minimum
b. an extreme value is sufficient for a stationary point
c.a local max or local min is a stationary point
d. All of above
e. none of the above (this is the answer)

What exactly are the questions in 1) and 2)?

In 3) a stionary point is a point where the tagent of the first differens are is zero. So an inflection point is also a stationary point. Therefore none of the ansewrs can be correct

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Rud Faden