数学题

jeans2011

If m is a positive odd integer between 2 and 30, then m is divisible by how many different positive prime numbers?   A
(1) m is not divisible by 3.
(2) m is not divisible by 5.
我觉得第二个也可以推出结论啊？
182. 17777-!-item-!-187;#058&011599
If m and r are two numbers on a number line, what is the value of r ?          E
(1) The distance between r and 0 is 3 times the distance between m and 0 .
(2) 12 is halfway between m and r.
这题有两个条件应该可以算出来吧？

annabelle0129

第一题条件二下，存在21，可以被3和7同时整除，而剩余的数只能被一个prime number整除，所以不对吧。
第二题就算有两个条件，算出来也有r=18,m=6和r=36,m=-12两种情况，所以选E吧。

jeans2011

谢谢！