CSULB No Absolute Minimum Values in The Functions Question

Question Description

I need an explanation for this Calculus question to help me study.

example: 

Find the critical points of the following function.

f(x)=4xx2+16

Select the correct choice below and, if necessary, fill in the answer box to complete your choice. 

A.

The critical point(s) occur(s) at x=nothing.

(Use a comma to separate answers as needed.)

B.

There are no critical points.

Find the absolute maximum and minimum values and their locations of the following functions on the given intervals

f(x) = sin(x+?2);[0,3?2]

f(x) = ln(x2+x+ 1); [?1,1]

g(x) = 6×5?5×6; (??,?)

h(x) = (9?x2)2/3?5; (??,0)