Minimize
My HomeMy ProfileMy AccountMy FriendsMy ChatboxSearch
Log InTurn Off
Guest
Page of 1
Displaying Posts 1 - 3 of 3
Jump to
Please Login or Register to Post Reply
Share/Save/Bookmark Login/ Register to Bookmark Topic : "quite a good one " Started by ~

~

#1 Posted 10:35am 10-03-10  

quite a good one

Write 271 as the sum of positive real numbers so as to maximize their product

[hide]more of calculus than algebra[4][/hide]
   

Asish

#2 Posted 11:17am 10-03-10  

Re: quite a good one

a1+a2+a3+....+an = 271

we need to maximise a1*a2*a3*....*an

from AM-GM

(271)/n ≥ (product)[p]1/n[/p]

=> product ≤ (271/n)[p]n[/p]

consider f(x) = (271/x)[p]x[/p]

lnf(x) = x*ln(271) - x*lnx
f'(x)/f(x) = ln(271) - 1 - lnx = 0
=> lnx = ln(271/e)

=> x = 271/e = 99.69

so 271 = e*(271/e)

each part is 271/e
IIT has walked to me ... off to IIT K    

~

#3 Posted 11:19am 10-03-10  

Re: quite a good one

correct :)
   
Please Login or Register to Post Reply
Page of 1
Displaying Posts 1 - 3 of 3