# 查看完整版本 : function問題

## function問題

Suppose f'(2)=13,g(7)=2 and g'(7)=53.if y=f(g(x)), find dy/dx when x=7

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iamnotaboy 2015-9-19 01:52 AM

y=f(g(x))
dy/dx = g'(x)f'(g(x))            ( since dy/dx = df(g(x))/dx = df(g(x))/dg(x) * dg(x)/dx )
when x=7
dy/dx = g'(7)f'(g(7)) = 53*f'(2) = 57*13 = 741

[quote]原帖由 [i]iamnotaboy[/i] 於 2015-9-19 01:52 AM 發表 [url=http://www.discuss.com.hk/redirect.php?goto=findpost&pid=426056536&ptid=25107774][img]http://www.discuss.com.hk/images/common/back.gif[/img][/url]
y=f(g(x))
dy/dx = g'(x)f'(g(x))            ( since dy/dx = df(g(x))/dx = df(g(x))/[color=#ff0000]dg(x) * dg(x)[/color]/dx )
when x=7
dy/dx = g'(7)f'(g(7)) = 53*f'(2) = 57*13 = 741 [/quote]路過想問呢步點解？係m2野？

14c14c 2015-9-19 03:38 PM

[quote]原帖由 [i]我要食甜蝦[/i] 於 2015-9-19 11:50 AM 發表 [url=http://www.discuss.com.hk/redirect.php?goto=findpost&pid=426073310&ptid=25107774][img]http://www.discuss.com.hk/images/common/back.gif[/img][/url]

https://notendur.hi.is/vae11/%C3%9Eekking/principles_of_mathematical_analysis_walter_rudin.pdf
pdf page 114/351 or p.105 in the original book

iamnotaboy 2015-9-19 11:23 PM