隐函数微分法证明2.

如题所述

第1个回答  2015-03-24
y = f(x,t),
t = t(x,y).

x是自变量,y,t都是因变量。
dy/dx = f'(x) + f'(t)dt/dx,

F(x,y,t) = 0.
F'(x) + F'(y)dy/dx + F'(t)dt/dx = 0,
dt/dx = [F'(x) + F'(y)dy/dx]/[-F'(t)].

dy/dx = f'(x) + f'(t)dt/dx = f'(x) + f'(t)[F'(x) + F'(y)dy/dx]/[-F'(t)],
[-F'(t) - f'(t)F'(y)]dy/dx = f'(t)F'(x) - f'(x)F'(t),

dy/dx = [f'(x)F'(t) - f'(t)F'(x)]/[F'(t) + f'(t)F'(y)]

证毕。本回答被提问者采纳
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