问题 解答题
计算.
(1)
x+2
2-x
4-x2
x2+2x

(2)
1-y
y2-4y+4
÷
y2-1
y2-4
答案

(1)原式=

x+2
-(x-2)
-(x+2)(x-2)
x(x+2)

=

x+2
x

(2)原式=

-(y-1)
(y-2)2
(y+2)(y-2)
(y+1)(y-1)

=-

y+2
(y-2)(y+1)

单项选择题 A1/A2型题
名词解释