www.whkt.net > ΪʲôDx=2tDt

ΪʲôDx=2tDt

DzûԪֵ? x=t^2,Ȼ΢,:dx=2tdt xxĵ1,΢ dxұt^2tĵ 2t,΢ 2tdt

ߡ(1+x)=t,1+x=t^2,x=t^2-1,dx=d(t^2-1)=d(t^2)=2tdt.

һ:,еڶֻԪ,ͼ,Ϊʲôdx=2tdt

Ϊdx=d[(t^2-1)/2]=d(2t/2)=dt

һ΢ְ,x=t+1,x,tԱ,xt󵼾2t,΢ٳdt,dx=2tdt

ֻԪ,x=t,ʽͬʱ΢־͵õdx=2tdt

ӢŶΪ~ ȫ΢ѧ,ʽ,ȫ΢ x^2=t^2-1,΢,2xdx=2tdt, ûѧĻҲ x=(t^2-1) x'=dx/dt=2t/2(t^2-1) xdx/dt=t,dt˵Ⱥұ߼

t=2x ƽ x=1/2*t^2 dx=d(1/2*t^2)=tdt

,ٵ󵼵˼ٿô˵.

Ӧ˻Ԫx=t^2/2,Ϊdx=d(t^2/2)=tdt,2dx=2tdt

վͼ

All rights reserved Powered by www.whkt.net

copyright ©right 2010-2021
www.whkt.net磬ַϵͷzhit325@qq.com