问题描述：
这是英文版数学分析的题,实在看不懂,求教!
Suppose that f and g are functions such that g ◦ f is onto.Must g be
onto?Should f be onto?（g、f是两个函数的表示~）
还有那个好多题里出现onto ,
Suppose that f and g are functions such that g ◦ f is onto.Must g be
onto?Should f be onto?（g、f是两个函数的表示~）
还有那个好多题里出现onto ,
问题解答：
我来补答展开全文阅读