Question

A rectangle has perimeter of 40 meters. What length and width yield the maximum area?

Answer 1

2l + b = 40

Answer 2

maximize A = lb

Answer 3

A = l (40-2l)

Answer 4

l = length, b = width

Answer 5

only problem is with your reasoning @Kanwar245 is it should be:

2l + 2b = 40
not
2l + b = 40

which means

A = l (40-2l)
is actually A = l(40-2l)/2

which means A = -l^2 + 40l

Answer 6

err i meant -l^2 + 20l at the end there.

regardless it's easier to solve when it's A = l(20-l)

Answer 7

thank you!!