#1

The top and bottom margins of a poster are 8 cm and the side margins are each 9 cm. If the area of printed material on the poster is fixed at 384 square centimeters, find the dimensions of the poster with the smallest area.

I did these steps:

xy = 384

y = 384/x

A = (x + 16) * (y + 18)

A = (x + 16) * (384/x + 18)

And I appear to be stuck at this step, the book doesn't have an examples listed for this problem either.

What would the answer be?

#2

Consider the function whose second derivative is . If and , what is ?

I've always had trouble with second derivatives, so an answer to this problem with an explanation would greatly help me! Much thanks again!