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____________.
当x=__________时,分式有意义.