1/5单选题
难度：
1.下列式子中一定是二次根式的是（）
| A |  |
| B |  |
| C |  |
| D |  |
- 提示1：
- 5LqM5qyh5qC55byP55qE5a6a5LmJ77ya5b2i5aaCPGltZyB3aWR0aD0xNyBoZWlnaHQ9MjEgc3JjPSJodHRwczovL3AyLnFpbmdndW8uY29tL0cxL00wMC8zRS9BOS9yQkFDSmxUSW1QR3pRcnRJQUFBQmcwam9YdjAzNDYucG5nIj7nmoTlvaLlvI/vvIhhPGltZyB3aWR0aD0yMiBoZWlnaHQ9MjEgc3JjPSJodHRwczovL3AyLnFpbmdndW8uY29tL0cxL00wMC8zRS9BQS9yQkFDSmxUSW1QR3hDNTVoQUFBQlBnYUd4dG8yNTkucG5nIj7vvInlj6vkuozmrKHmoLnlvI8=
正确答案：Qg==
6Kej562U77ya5qC55o2u5LqM5qyh5qC55byP55qE5a6a5LmJ77yMQi4gPGltZyB3aWR0aD0yOSBoZWlnaHQ9MjUgc3JjPSJodHRwczovL3AyLnFpbmdndW8uY29tL0cxL00wMC9BQS8yNy9yQkFDRkZUSW1QR3lQWjNJQUFBQmNqdVBwc1k3ODgucG5nIj48YnI+4oi1PGltZyB3aWR0aD00MSBoZWlnaHQ9MjEgc3JjPSJodHRwczovL3AyLnFpbmdndW8uY29tL0cxL00wMC8zRS9FOC9yQkFDSjFUSW1QR0JIMURqQUFBQm5SOWlDUUk2MzIucG5nIj48YnI+5pWF6YCJQjxicj4=
2/5单选题
难度：
2.若
是二次根式，则a，b应满足的条件是（）
是二次根式，则a，b应满足的条件是（） | A | a≥0，b≥0 |
| B | a≥0，b＞0 |
| C |  |
| D |  且b |
- 提示1：
- 5LqM5qyh5qC55byP55qE5a6a5LmJ
正确答案：RA==
6Kej562U77ya4oi16IulPGltZyB3aWR0aD0yNiBoZWlnaHQ9NDIgc3JjPSJodHRwczovL3AxLnFpbmdndW8uY29tL0cxL00wMC9BQS8yNy9yQkFDRkZUSW1RREJTcG54QUFBQnVqUVNWdUU0MDYucG5nIj7mmK/kuozmrKHmoLnlvI88YnI+4oi0PGltZyB3aWR0aD0zNiBoZWlnaHQ9Mzggc3JjPSJodHRwczovL3AxLnFpbmdndW8uY29tL0cxL00wMC8zRS9BQS9yQkFDSmxUSW1RQ1JZbWUzQUFBQjZIV2ZtSk05MzMucG5nIj7kuJRiPGltZyB3aWR0aD0yMiBoZWlnaHQ9MjEgc3JjPSJodHRwczovL3AxLnFpbmdndW8uY29tL0cxL00wMC8zRS9FOC9yQkFDSjFUSW1RQ3paNllUQUFBQlFTZ25yUVU5NDgucG5nIj48YnI+5pWF6YCJRA==
3/5单选题
难度：
3.
当x=-3时，下列各式没有意义的是（ ）
| A |
|
| B |
|
| C |
|
| D |
|
- 提示1：
- PHA+5LqM5qyh5qC55byP6KKr5byA5pa55pWw5Li66Z2e6LSf5pWwPC9wPg==
正确答案：Qw==
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
4/5单选题
难度：
4.a为实数，下列式子的值中一定是非负数的是（）
| A | |
| B |  |
| C |  |
| D |  |
- 提示1：
- 5LqM5qyh5qC55byP55qE5Y+M6YeN6Z2e6LSf5oCn
正确答案：QQ==
6Kej562U77ya4oi1PGltZyB3aWR0aD00MyBoZWlnaHQ9MjEgc3JjPSJodHRwczovL3AyLnFpbmdndW8uY29tL0cxL00wMC8zRS9BQS9yQkFDSmxUSW1RcXk3VWhFQUFBQjBSQTZBYU05NjkucG5nIj7vvIxhPGltZyB3aWR0aD0yMiBoZWlnaHQ9MjEgc3JjPSJodHRwczovL3AyLnFpbmdndW8uY29tL0cxL00wMC8zRS9BQS9yQkFDSmxUSW1QR3hDNTVoQUFBQlBnYUd4dG8yNTkucG5nIj48YnI+5pWFQS48aW1nIHdpZHRoPTI5IGhlaWdodD0yNSBzcmM9Imh0dHBzOi8vcDIucWluZ2d1by5jb20vRzEvTTAwL0FBLzI3L3JCQUNGRlRJbVBHeVBaM0lBQUFCY2p1UHBzWTc4OC5wbmciPueahOWAvOS4gOWumuaYr+mdnui0n+aVsDxicj4=
5/5单选题
难度：
5.已知
，则2xy的值为（）
，则2xy的值为（） | A | -15 |
| B | 15 |
| C |  |
| D |  |
- 提示1：
- 5LqM5qyh5qC55byP6KKr5byA5pa55pWw5Li66Z2e6LSf5pWw
正确答案：QQ==
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