问题
填空题
若x+y=3,y+z=4,z+x=5,则x+y+z=______.
答案
∵x+y=3,y+z=4,z+x=5,
∴x+y+y+z+z+x=12,
∴2x+2y+2z=12,
∴x+y+z=6.
故填:6
若x+y=3,y+z=4,z+x=5,则x+y+z=______.
∵x+y=3,y+z=4,z+x=5,
∴x+y+y+z+z+x=12,
∴2x+2y+2z=12,
∴x+y+z=6.
故填:6