导数y(x,t)对t求导怎么求.我这题是y(x

如题所述

第1个回答  2018-01-07
令x= f(t),y=g(t),
那么y '(x)= (dy/dt) / (dx/dt) = g '(t) / f '(t),

y''(x)
= d[y '(x)] /dx
= d[y '(x)] /dt * dt/dx
= d[g '(t) / f '(t)] /dt * 1/ f '(t),
= [g "(t) * f '(t) - g '(t) * f "(t) ] / [f '(t)]^3本回答被网友采纳