中考数学专题《代数式》复习试卷(含解析)

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1、2018年中考数学专题复习卷:代数式一、选择题1.以下各式不是代数式的是（  ）A. 0                                       B.                                        C.                                        D. 2.若单项式am﹣1b2与 的和仍是单项式，则nm的值是（  ）A. 3                                           B. 6                               

2、            C. 8                                           D. 93.某一餐桌的表面如图所示（单位：m），设图中阴影部分面积S1，餐桌面积为S2，则（   ）A.                                           B.                                           C.                                           D. 4.若M=3x2﹣8xy+9y2﹣4x+6y+13（x，y是实数），则M的

3、值一定是（  ）A. 零                                      B. 负数                                      C. 正数                                      D. 整数5.代数式相乘，其积是一个多项式，它的次数是（  ）A. 3                                           B. 5                                           C. 6                   

4、                        D. 26.已知a+b=5，ab=1,则（a-b）2=(      ）A. 23                                         B. 21                                         C. 19                                         D. 177.若

5、x+2y+3

6、与（2x+y）2互为相反数，则x2﹣xy+y2的值是（ ）A. 1                                      

7、     B. 3                                           C. 5                                           D. 78.已知a、b满足方程组，则3a+b的值为（  ）A. 8                                         B. 4                                         C. ﹣4                                         D. ﹣89.黎老师做了个长方形教具，其

8、中一边长为2a+b，另一边为a-b，则该长方形周长为（     ）A. 6a                                     B. 6a+b                                     C. 3a                                     D. 10a-b10.A地在河的上游，B地在河的下游，若船从A地开往B地的速度为V1，从B地返回A地的速度为V2，则A，B两地间往返一次的平均速度为（  ）A.                                 B.        

9、                         C.                                 D. 无法计算11.如图，都是由同样大小的圆按一定的规律组成，其中，第①个图形中一共有2个圆；第②个图形中一共有7个圆；第③个图形中一共有16个圆；第④个图形中一共有29个圆；…；则第⑦个图形中圆的个数为(  )A. 121                                      B. 113                                      C. 105                        

10、