若当x=2时,分式没有意义,则a=____________.
如果分式的值为0,则x的值是_____________.
分式与
的最简公分母是____________.
计算:
(1)+
=____________
(2)()2=_____________
(3)+
=_______________
(4)-
=____________
(5)1÷(+
)=_________________
约分:(1)=_________________(2)
=________________
当x=1,y=-4时,分式的值是____________.