→ ntust661 :看不到Partial! 11/03 20:09
→ rockdancer :第3題的正方形框框就是partial符號，我打不出來抱歉! 11/04 01:41
這幾題小弟不會解
不知道版上有沒有高手願意教一下的
謝謝!!
1. Let f(x) = x if x is rational , f(x) = 0 if x is irrational.
Show that f is continuous at x = 0 and nowhere else.
2. Show that an infinite set S 包含於 R^n(空間) is compact if and only if
every
infinite subset of S has an accumulation point that lies in S.
3. If u = x^2 + 3*y^2 and y = x*z , there are two possible meanings for ∂u/
∂x depending on whether the independent variables are taken as (x , y) or
(x, z) .
Compute both them.
註：第3題的 "∂" 是偏微(partial)的符號。
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