5.下列各式的值一定是正数的是( )
| A. | |a| | B. | $\sqrt{a^2}$ | C. | $\frac{1}{a^2}$ | D. | $\root{3}{a}$ |
4.下列代数式:$\frac{x}{2}$,$\frac{x}{m}$,2x-y,(1-20%)x,$\sqrt{2}$ab,$\frac{x}{x+y}$,$\root{3}{a}$,其中是整式的个数是( )
| A. | 2 | B. | 3 | C. | 4 | D. | 5 |
3.下列各组中的两项是同类项的是( )
| A. | 3a2b与ab2 | B. | a2b与ba2 | C. | 3ab与a | D. | 2与3x |
18.九年级三班同学做了关于私家车乘坐人数的统计,在100辆私家车中,统计如表:
根据以上结果,估计抽查一辆私家车且它载有超过3名乘客的概率是$\frac{7}{100}$.
0 293909 293917 293923 293927 293933 293935 293939 293945 293947 293953 293959 293963 293965 293969 293975 293977 293983 293987 293989 293993 293995 293999 294001 294003 294004 294005 294007 294008 294009 294011 294013 294017 294019 294023 294025 294029 294035 294037 294043 294047 294049 294053 294059 294065 294067 294073 294077 294079 294085 294089 294095 294103 366461
| 每辆私家车乘客的数目 | 1 | 2 | 3 | 4 | 5 |
| 私家车的数目 | 58 | 27 | 8 | 4 | 3 |