已知x-y=3-1，xy=123，则x2+y2=______．_爱下问搜题

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问题填空题

已知x-y=

3

-1，xy=

1

2

3

，则x²+y²=______．

答案

∵x-y=

3

-1，xy=

1

2

3

，

∴x²+y²=（x-y）²+2xy

=（

3

-1）²+

3

=4-2

3

+

3

=4-

3

．

故本题答案为：4-

3

．

选择题

— Come and join us, Ben!

— I’m afraid I can’t. I’m too busy now. If I ________ time, I would certainly go.

A．had

B．will have

C．have had

D．have

问答题简答题

杂文的证论因素和文艺因素？