谢谢版主，还有疑问

wister

版主谢谢你 K＝0.1－（0.1）^2 问x>0.05? a. k>0.009/x b k<0.0009/x .但是，第一个条件中，X<0也可以成立，所以我认为A仍然不对。 另外一题 20．If x and y are positive integers such that x=8y+12,what is the greatest common divisor of x and y? 1) x=12u,where u is an integer 2) y=12z,where z is an integer HOW TO DEAL WITH THIS KIND OF QUESTION? 谢谢！