11
Devil
·2009-12-19 08:31:44
The 1st qsn simply requires a factorisation and the fact that 7 is prime....
13
Avik
·2009-12-20 05:51:28
Hey, i did smthing...! But it needs 2b verified 1st..
Q1) Writing as-
2(x+y)(x-y) -3xy =7
So, v need to find, α & β such tht...
2α - 3β =7
Taking- α=8, β=3 satisfies.
So, xy=3 & , x2-y2 =8
Solving fr x, we get ......x=±3 => y= ±1
Hence integral solutions = 2
Okay, so this finally giving the answer, but how do v convince ourselves tht there are no other values of α,β satisfying the above condition & giving integral solutions fr x & y....?
Also, the 2nd one's left still...
11
Devil
·2009-12-20 06:23:17
Why don't u simply write the 1st expression as (2x+y)(x-2y)=7....? Where do u get alpha-beta and all those stuff?
13
Avik
·2009-12-20 06:30:24
Arrey, am telling u, this factorisation thing never clicks me at all...!! Have tried a lot !
Theek hai... (2x+y)(x-2y)=7, phir next ?
11
Devil
·2009-12-20 06:32:10
AAre....now since 7 is prime, so only factors are 7 and 1, so either 2x+y=7 (or 1), similarly x-2y=1 (or 7), now simultaneously solve both. Any more doubts?
13
Avik
·2009-12-20 06:38:46
lol....thnx
Now, 2nd waala left.
Am still laughing ... lol..
11
Devil
·2009-12-20 06:41:34
2nd wala -- - - - - -
I'm feeling lazy to go for it, u just need to take a few intervals for this....
13
Avik
·2009-12-20 06:45:28
2nd waala ho jayegaa ab, i think, wahi mod ki Qty ko +ve/-ve lena hai na; with appropriate intervals ? Then, graph...