Here is another more direct proof so that you can check the prob

来源: aisanguo 于 2012-03-11 19:56:30 [] [博客] [旧帖] [给我悄悄话] 阅读数 : (235 bytes)
本帖于 2012-06-08 15:17:10 时间, 由版主 idiot94 编辑
回答: THANKS,PLESE TRY THIS;XX+4XY+YY=69,NO SOLUTION. 由 jinjing 于 2012-03-11 19:29:43

Suppose

x=(a+b)^2+2*a*b,

y=(c+d)^2+2*c*d,

then after some simple calculation, one can check that

xy=(u+v)^2+2*u*v,

whereu=a*c+b*d and v=a*d+b*c+4*b*d.

In your example, F(-13,2)=69.

所有跟帖： 

• I'M WRONG,YOU ALSO WRONG.I'LL DO IT BY PEN TOMORROW. -jinjing- ♀ 给 jinjing 发送悄悄话 (0 bytes) () 03/11/2012 postreply 20:40:24

• Thanks for pointing it out. It seems just a typo. -AiSanGuo- ♀ 给 AiSanGuo 发送悄悄话 AiSanGuo 的博客首页 (0 bytes) () 03/11/2012 postreply 21:50:35

• Sorry, there is a typo: u should be a*c-b*d -AiSanGuo- ♀ 给 AiSanGuo 发送悄悄话 AiSanGuo 的博客首页 (0 bytes) () 03/11/2012 postreply 21:13:05

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