7. square is just a special case of rectangle whose adjacent sides are equal.
let's denote one of the sides as a and the other as b thus:
now let's differentiate S(a):
you can differentiate S one more time to make sure that it's maxima.
I just need help on questions 7, 8, 9, 12, and 13
For question 7, I keep thinking that the pool area is a square, so wouldn't all sides be equally fenced? Therefore wouldn't the 25M be equally divided by 4 to maximize area?
Thank-you in advance