121*25+625*12+144*11=...?
A) less than 11*25*12
B) less than 2*11*25*12
C)less than 3*11*25*12
D) greater than or equal to 3*11*25*12

• if x=11 , y=25, z=12 then
  
  121*25+625*12+144*11 = ( x^2*y +y^2*z + z^2*x )
  
  apply A.M > = GM
  
  => ( x^2*y +y^2*z + z^2*x ) / 3 > = [x^2y*y^2z*z^2x]^(1/3)
  
  => ( x^2*y +y^2*z + z^2*x ) > = 3xyz
  
  i.e greater than or equal to 3*11*25*12.
• 9 years agoHelpfull: Yes(3) No(0)