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问题 填空题
已知m和n是方程2x2-5x-3=0的两根，则
1
m
+
1
n
=______．
答案

∵m和n是方程2x2-5x-3=0的两根，

∴m+n=-

b
a
=-
-5
2
=
5
2
，m•n=
c
a
=-
3
2
，

∴

1
m
+
1
n
=
m+n
mn
=
5
2
-
3
2
=-
5
3

故答案为-

5
3
．

选择题

—What would you like to say to your ________ before leaving school?

—I’d like to say “Thank you very much! I’ve learnt a lot from you in the past three years.”

A．teachers

B．workers

C．doctors

D．engineers
查看答案
填空题

路基挡土墙伸缩缝应沿挡土墙纵向每隔（）或在与其他建筑相接处设置。
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