Question

已知x减y等于负二;x加y等于1,问x等于几,y等于几.

Answer 1

x-y=-2 ①

x+y=1 ②

把①+②得

x-y+x+y=-2+1

2x=-1

x=-1/2

把x=-1/2代入②得

(-1/2)+y=1

y=1-(-1/2)

=3/2

∴x=-1/2,y=3/2

即x=-0.5,y=1.5