sinxy-ln(x+y)=0两边对X求导 cos(xy)(y+xy')-(1+y‘)/(x+y)=0 其中(1+y‘)/(x+y)怎么得来的?
问题描述:
sinxy-ln(x+y)=0两边对X求导 cos(xy)(y+xy')-(1+y‘)/(x+y)=0 其中(1+y‘)/(x+y)怎么得来的?
答
ln(x+y)求导=1/(x+y)*(x+y)'
=1/(x+y)*(1+y')
=(1+y')/(x+y)