问题 解答题
计算
(1)
x2+2xy+y2
x2-y2

(2)(
4
x2-4
+
1
x+2
1
x-2

(3)(-
1
2
)-2+(
1
19
)0+(-5)3÷(-5)2
答案

(1)原式=

(x+y)2
(x+y)(x-y)
=
x+y
x-y

(2)原式=

4+x-2
(x+2)(x-2)
×(x-2)=
1
x-2
×(x-2)=1;

(3)原式=4+1-5=0.

单项选择题
单项选择题