[QUOTE=champrock;220156]A> if a function is f(x) defined in R--> R,STRICLTYincreasing and differentiable.. then the derivative of f:

a. May be less than 0 at some x.

b. May be infinite at some x.

c. is greater than or equal to 0 at every x belonging to R

d. is greater than 0 at every x belonging to R

I think the answer is "d" but I am not too sure as it can be 0 also at some point? This is because the second question has confused me a bit.[quote]

Consider the function .

Now look at .=-===========================

B> Consider a strictly decreasing function which is differentiable. Which of the following"may be true"about the derivative of f.

a. derivative > 0 for some x belonging to R

b. derivative = 0 for some x belonging to R

c. derivative = 0 for every x belonging to (a,b) where a<b.

d. derivative >= 0 for every x belonging to R

i think the ideal answer should have been "less than 0" but since that option is not there at all, i am slightly confused.