討論版

回覆主題：證明題....

1. Prove that E={(x,y) in R^2 : y < x^2} is open in R^2 with the closure E"={(x,y) in R^2 : y <= x^2}. 2. Prove that a set D in R^k is dense if and only if U交集D不等於空集合 for every nonempty open subset U in R^k. 麻煩大家了...>"<~~... 　

討論內容：
姓名		email
留言