解 1+X=(A+B+C)/B+C 1+Y=(A+B+C)/A+C 1+Z=(A+B+C)/A+B
X/(1+X)= A/(A+B+C) Y/(1+Y)=B/(A+B+C) Z/(1+Z)=C/(A+B+C)
故 X/1+X+Y/1+Y+Z/1+Z=A/(A+B+C)+B/(A+B+C)+C/(A+B+C)=(A+B+C)/(A+B+C) =1
解 1+X=(A+B+C)/B+C 1+Y=(A+B+C)/A+C 1+Z=(A+B+C)/A+B
X/(1+X)= A/(A+B+C) Y/(1+Y)=B/(A+B+C) Z/(1+Z)=C/(A+B+C)
故 X/1+X+Y/1+Y+Z/1+Z=A/(A+B+C)+B/(A+B+C)+C/(A+B+C)=(A+B+C)/(A+B+C) =1