练习四第1题答案
(1) | (2) | (3) | (4) | (5) |
√ | × | × | √ | √ |
练习四第2题答案
(1) | (2) | (3) | (4) | (5) |
B | C | C | B | A |
练习四第3题答案
(1)6,12,18,24,30,36
(2)无限 它本身
(3)20 5和4 4和5 20
(4)奇数有:11,13,15,17,19
偶数有:10,12,14,16,18,20
质数有:11,13,17,19
合数有:10,12,14,15,16,18,20
(5)2的倍数:18,90,130
5的倍数:75,90,130
3的倍数:18951,63,75,90,
2、3和5的倍数:90
(6)20
(7)6
练习四第4题答案
13,26,39,52,65,78,91
练习四第5题答案
(1)1,15,3,5
(2)1,24,2,32,3,8,4,6
(3)1,18,2,9,3,6
(4)1,20,2,10,4,5
练习四第6题答案
(1)1,25,5
(2)25,50,75,100
(3)25
练习四第7题答案
奇数有:1,35,37,9,11,25,21,23
偶数有:12,10,54,6,8
质数有:37,11,23
合数有:12,35,10,54,9,25,6,8,21
练习四第8题答案
(1)2 0
(2)0
(3)1 0