I don't think so: 回复：ＴＨＥ Q IS ＷＲＯＮＧ，

4*22=88=(-6)^2+4*(-6)*26+26^2=F(-6,26), so 88 belongs to A as well.

所有跟帖： 

• THANKS,PLESE TRY THIS;XX+4XY+YY=69,NO SOLUTION. -jinjing- ♀ (51 bytes) () 03/11/2012 postreply 19:29:43

• Here is another more direct proof so that you can check the prob -aisanguo- ♀ (235 bytes) () 03/11/2012 postreply 19:56:30

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

• Thanks for pointing it out. It seems just a typo. -AiSanGuo- ♀ (0 bytes) () 03/11/2012 postreply 21:50:35

• Sorry, there is a typo: u should be a*c-b*d -AiSanGuo- ♀ (0 bytes) () 03/11/2012 postreply 21:13:05

• F(2,5)=69 or F(-2,-5)=69, I think the Q is right. -万斤油- ♂ (0 bytes) () 03/11/2012 postreply 20:03:06