问题 解答题
计算:
(1)(π-
3
0+(
1
3
-2+
18
;   
(2)(x+y)2-(x-y)2
答案

(1)原式=1+9+3

2

=10+3

2

(2)原式=x2+2xy+y2-(x2-2xy+y2

=x2+2xy+y2-x2+2xy-y2

=4xy.

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