sci.math
[Top] [All Lists]

Re: a few more general GRE math problems

Subject: Re: a few more general GRE math problems
From: "Nick"
Date: Sun, 31 Dec 2006 11:05:02 -0000
Newsgroups: sci.math
"john" <johnboy98105@xxxxxxxxx> wrote in message 
news:1167557963.377775.165150@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
>
>
> Q2:
>  x > 1
>  y > 1
>
> What is greater?  1 / ( 1/x + 1/y)  or 1/x + 1/y     that is...
>
> a.                                   b.
>         1                                 1            1
> -------------------          or          -------  +   ------
>   1         1                             x           y
> -------  + ------
>   x         y
>
>
>
> A2: Need more information to determine the relationship.
>
>
> I got this one wrong after plugging in x = 2, y = 3
>
> so i figured....
>
> a.   xy                      b.   y + x
>   ----------                       ----------
>    x + y                           xy
>
>       6/5            >            5/6
>
> or if x= 2, y = 5
>
> then
>         10/7         >         7/10
>
>
> or if x = 5, y = 5
>
> then    25/10      >      10/25
>
> I can't get why you need more info to determine the relantionship..
> What's the trick here?

When x=2, y=2 then a) =4/4 and b) =4/4

So in this particular instance, a) = b)

x=1.5, y=1.5 then a) = 2.25/3 b) = 3/2.25

In this instance, b) > a)

Nick 



<Prev in Thread] Current Thread [Next in Thread>
Privacy Policy