Problema Solution

A carpenter is building a rectangular room with a fixed perimeter of 320 ft. What dimensions would yield the maximum area? What is the maximum area?

Answer provided by our tutors

so 240=2*(l+b)so 

l+b=120

so if l=x

b=120-x

area=x*(120-x)

A=x(120-x)

for maximum A dA/dx=0

dA/dx=d/dx(120x-x^2)

0=120-2x

x=60ft

length=60ft

breadth=120-60=60ft answer

area  =  60* 60  =  3600  sq  ft