问题 解答题
已知x=
3
+
2
3
-
2
,y=
3
-
2
3
+
2
,求
x3-xy2
x4y+2x3y2+x2y3
的值.
答案

∵x=

(
3
+
2
)2
(
3
-
2
)(
3
+
2
)
=5+2
6
,y=
(
3
-
2
)2
(
3
-
2
)(
3
+
2
)
=5-2
6

∴x+y=10,xy=25-24=1,x-y=4

6

∴原式=

x(x-y)(x+y)
x2y(x2+2xy+y2)

=

(x-y)(x+y)
xy(x+y)2

=

x-y
xy(x+y)

=

4
6
1×10

=

2
6
5

判断题
单项选择题 A1/A2型题