※ 引述《zergcho (ZC)》之銘言：
: 請教各位應該如何解...
: XY-17=X+Y
: YZ-27=Y+Z
: XZ-13=X+Z
: 好像有兩組實數解...
: 謝謝!!
XY-X-Y+1=18=(X-1)(Y-1)
YZ-Y-Z+1=28=(Y-1)(Z-1)
XZ-X-Z+1=14=(X-1)(Z-1)
[(X-1)(Y-1)(Z-1)]^2=18*28*14
(X-1)(Y-1)(Z-1)=±84
CASE I (X-1)(Y-1)(Z-1)=84
(Z-1)=84/18=14/3 => Z=17/3
(X-1)=84/28=3 => X=4
(Y-1)=84/14=6 => Y=7
CASE I (X-1)(Y-1)(Z-1)=-84
(Z-1)=-84/18=-14/3 => Z=-11/3
(X-1)=-84/28=-3 => X=-2
(Y-1)=-84/14=-6 => Y=-5
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