中考数学专题-------二次根式化简求值.docx

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1、专题练习-二次根式化简求值一、单选题1.计算的结果（）A.                                     B. -                                    C.                                     D. -2.若，化简=(  )A.                                  B.                                  C.                                  D. 3.先化简

2、再求值：当a=9时，求a+的值，甲乙两人的解答如下：甲的解答为：原式=；乙的解答为：原式=．在两人的解法中（  ）A. 甲正确                              B. 乙正确                              C. 都不正确                              D. 无法确定4.当x=-2时，二次根式的值为(    )A. 1                                          B. ±1                              

3、            C. 3                                          D. ±35.已知，则代数式的值是（   ）A. 0                                    B.                                     C.                                     D. 6.已知x=-5，则代数式（x+4）2的值为（ ）A. 3﹣2                           B. 2+2           

4、                C. 1﹣                           D. 3+27.若化简

5、的结果是，则x的取值范围是（  ）A. x为任意实数                               B. 1≤x≤4                               C. x≥1                               D. x＜48.设a为﹣的小数部分，b为﹣的小数部分．则﹣的值为（　　）A. +-1                        B. -+1           

6、             C. --1                        D. ++19.设实数a，b在数轴上对应的位置如图所示，化简+

7、a+b

8、的结果是（  ）A. -2a+b                                      B. 2a+b                                      C. -b                                      D. b10.若，则xy的值为（　　）A. 3                                

9、           B. 8                                           C. 12                                           D. 411.下列计算中，正确的有（ ）①=±2 ；②=2； ③=±25；④a=－ A. 0个                                       B. 1个                                       C. 2个                                   

10、    D. 3个12.设＝a，＝b，用含a，b的式子表示，下列正确的是(  )A. 0.3ab2                                 B. 3ab                                 C. 0.1ab3                                 D. 0.1a3b13.已知x+

11、x-1

12、=1，则化简的结果是（    ）A. 3-2x                                       B. 1                          

13、             C. -1                                       D. 2x-314.已