已知点（-1,-1）在直线ax+by+2=0(a>0,b>0)上,则1a+1b的最小值为( )_刷题宝

题干

已知点（-1,-1）在直线ax+by+2=0(a>0,b>0)上,则

1

a

+

1

b

的最小值为( )

A：1

B：2

C：3

D：4

上一题下一题 0.0难度选择题更新时间:2017-05-05 05:19:41

答案(点此获取答案解析）

B

同类题1

某化学式为AB的离子晶体，已知5r(A²⁺)=4r(B^2-）（各类离子晶体与

关系如下图所示），经测定其密度为

g·cm^-3，其摩尔质量为Mg·mol^-1，则下列有关该晶体的说法正确的是（　　）

同类题2

计算：y（2x﹣y）+（x+y）²

同类题3

将词语补充完整，再选择填空。
____今中____ 情不自____ 地____天____ ____壮成长
①在老师的辛勤培养下，我们____，不断进步。
②暑假里，我阅读了____的名著，大开眼界。
③狐狸见乌鸦叼着一片肉，____地流下口水。

同类题4

参与民主选举是我国公民政治生活的重要内容。下列关于选举方式的说法正确的是

同类题5

任务型阅读

　　At present, there is much homework for American students. But home is not a good place for students to do their homework. So there come Homework Clubs. And they are more and more popular in America.

What is the Homework Club?

The Homework Club is a good place for students to do their homework. It is very quiet. A teacher will help students prepare for the tests there. The teacher is not to teach students but to give them help when they need.

Where is the Homework Club?

The Homework Club is usually in a library or in a classroom. It is a popular activity after school every day. If there is no school that day, Homework Clubs will NOT meet.

What will students do in the Homework Club?

In the Homework Club, the students will do their homework for the first hour and then they will draw pictures or play football.

根据短文内容填空。

小学学科试题库

初中学科试题库

高中学科试题库