What is the maximum area possible when 138 feet of fence is used to enclose a rectangular dog pen?

• given:2(l+b)=138
  =>l+b=69
  let l=x(length);
  b=69-x(breadth);
  area=A;
  A=l*b;
  A=x*(69-x)
  A=69*x-x^2;
  so, for maxima we put dA/dx=0
  dA/dx=69-2*x=0
  x=69/2;
  i.e l=69/2;
  b=69/2;
  so, max(A)=(69/2)*(69/2)
  =1190.25 sq.feet
• 10 years agoHelpfull: Yes(1) No(0)
• 2(l+b)=138
  now l+b=69
  choose value of l and b so that l*b=maximum and also qualifies above equation
  for l and b equals to 36 and 33..
  l*b=1188 which is maximum
  
• 10 years agoHelpfull: Yes(0) No(0)