DSE 2006

[s]

thanks :)

[aditi5000]

Hey did anyone think about question 52.. DSE 2006.. it says f is strictly increasing i.e. if x>y then f(x) > f(y) ..so  shouldn't f'(x)  be strictly greater than zero ??
if it is = to zero then that means the function itself must be a constant function.. (or it could be a critical point...) but a constant function is not strictly increasing or strictly decreasing... so how does this make sense? is this a reference to critical points of inflection where the rate of increase is changing ? from concave to convex or vice versa?
why is it c.. and not d?

And have a look at question 13 DSE 2007.. It's asking the same question but for decreasing functions.. and the answer is part b ie.. f'(x)=0 for some x.. these two questions don't seem to make sense when they are put together.. Please help :( Thank you in advance!

[sonudelhi]

thank so much chinni ,it was so helpful....

Can you tell me any book for lots of pure exchange problems?

[Chinni18]

You're welcome sonudelhi. You can try varian workbook. Or just look online for problem sets on general equilibrium, there are a lot of notes available. You only need to know the concept very well, then you can solve the questions quite easily  All the best!

[Chinni18]

Hmm you're right aditi, it seems illogical but when put together both answers do bear each other out. The 2006 paper talks about increasing functions and the 2007 paper talks about decreasing functions but both say that it is possible for the derivative to be equal to zero. But I don't understand why. If the graph is flat at any point then the definition of strictly increasing or strictly decreasing won't hold.

[aditi5000]

if f'x = 0 then it can still be strictly increasing or decreasing IFF f'x=0 is a point of inflection where the second derivative changes from +ve to -ve or vice versa .. does that make sense? i.e. increasing at increasing rate to increasin at falling rate etc..

[Chinni18]

Oohhhhhh you're right!!!! Yes I never considered that!!! Then it makes perfect sense  

[rongmon]

Can someone share the workings for the Q 21, 22 and 23?

Thanks.