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Originally posted by gnome-kde at 2005-4-6 20:30:
* Y2 d. s. l7 m这样算混淆了微分和导数的概念。
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d(f(x))/dx = f'(x), d(f(x)g(x))/dx = f'(x) d(g(x))/dx + g'(x) d(f(x))/dx 这是基本的微分四则运算. k$ X8 {% L" Z2 Y
8 {# z3 X8 t3 O, Y2 BIf h(x)=(a+bx)*C(x)/x, then d(h(x))/dx = d{(a+bx)*C(x)/x}/dx = h ...
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8 D$ U, k e9 @; O这样算混淆了微分和导数的概念。
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d(f(x))/dx = f'(x), d(f(x)g(x))/dx = f'(x) d(g(x))/dx + g'(x) d(f(x))/dx 这是基本的微分四则运算3 i$ f7 t: l$ R8 v
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Ah, you made a mistake: it should be:
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5 ~% D2 G5 a; k; S# A4 Rd(f(x)g(x))/dx = f(x) d(g(x))/dx + g(x) d(f(x))/dx % F g# U; M# c8 {6 |( g( v+ M
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- |8 c# g ^# eIf h(x)=(a+bx)*C(x)/x, then d(h(x))/dx = d{(a+bx)*C(x)/x}/dx = h'(x) = [xb*c(x)+x(a+bx)*c'(x)-(a+bx)*c(x)]/x2 (应该对吧, 我也没验算)
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2 o5 i$ W7 K( I1 F. n% T6 o" o1 bfor h(x)=(a+bx)*C(x)/x, you are right, But, no x there, it is:
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" c) \2 j4 ?( f- X2 J' n# _: I; P! C" F: Lh(x)=(a+bx)*C(x) |
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