14.让我们轻松一下,做一个数字游戏:
第一步:取一个自然数x1=5,计算x12+1得y1;
第二步:算出y1的各位数字之和得x2,计算x22+1得y2;
第三步:算出y2的各位数字之和得x3,再计算x32+1得y3;
依此类推,则y30=( )
第一步:取一个自然数x1=5,计算x12+1得y1;
第二步:算出y1的各位数字之和得x2,计算x22+1得y2;
第三步:算出y2的各位数字之和得x3,再计算x32+1得y3;
依此类推,则y30=( )
| A. | 5 | B. | 26 | C. | 65 | D. | 122 |
13.运算结果为4x2-4xy+y2的是( )
| A. | (x-2y)2 | B. | (4x-y)2 | C. | (-2x-y)2 | D. | (2x-y)2 |
12.计算:(-3)2005×($\frac{1}{3}$)2006=( )
| A. | -1 | B. | 1 | C. | -$\frac{1}{3}$ | D. | $\frac{1}{3}$ |
11.下列算式能用平方差公式计算的是( )
| A. | (2a+b)(2b-a) | B. | (4x+1)(-4x-1) | C. | (2x-y)(2x-y) | D. | (-y+x)(-y-x) |
10.下列计算正确的是( )
| A. | x2+x4=x6 | B. | x9÷x3=x3 | ||
| C. | x2015+x2015=2x2015 | D. | (x3)3=x6 |
9.计算:a2•(-a)3的结果正确的是( )
0 309788 309796 309802 309806 309812 309814 309818 309824 309826 309832 309838 309842 309844 309848 309854 309856 309862 309866 309868 309872 309874 309878 309880 309882 309883 309884 309886 309887 309888 309890 309892 309896 309898 309902 309904 309908 309914 309916 309922 309926 309928 309932 309938 309944 309946 309952 309956 309958 309964 309968 309974 309982 366461
| A. | -a5 | B. | a5 | C. | -a6 | D. | a6 |