人教版八年级下册16.3 二次根式的加减第1课时习题

第1课时 二次根式的加减

1.下列各式能与合并的二次根式是 (   )

A.                  B.                    C.                  D.

2.若最简二次根式和能合并，则x的值可能为 (   )

A.x=-                                        B.x=1

C.x=-2                                         D.x=2

3.计算3-的值是 (   )

A.2                     B.3                  C.                  D.2

4.下列计算正确的是 (   )

A.2+=2                                 B.5-=5

C.+=                                D.-=

5.计算-的结果是 (   )

A.-                                        B.

C.-                                     D.

6.若与可以合并，则x可以是 (   )

A.0.5                                           B.0.4

C.0.3                                           D.0.2

7.下列计算正确的是 (   )

A.+=7                                    B.3-=3

C.×=                               D.=5

8.计算4+3-的结果是 (   )

A.+                                      B.

C.                                          D.-

9.计算|2-|+|4-|的值是 (   )

A.-2                                           B.2-6

C.2                                            D.6-2

10.若与可以合并，则a的最小正整数值是      

11.若一个长方形相邻的两条边长分别是 cm和 cm，则它的周长为       cm

12.计算：(1)-+=               (2)-=      

13.计算：-9+2=       

14.计算：当y=时，-的值是         

15.计算：

(1)-                   (2)+

(3)-+               (4)--

16.计算:

(1)-                     (2)++

(3)+-            (4)3-+-

(5)+-(+)       (6)(+6)-(-10)