兩種方法都是對(duì)的
直接做
dy/dx=(y-e^(x+y))/(e^(x+y)-x)
將e^(x+y)換成xy
即dy/dx=[y-xy]/[xy-x]
ln(xy)=x+y 再在兩邊對(duì)X求導(dǎo)
→ (1/xy)*(y+x*(dy/dx))=1+dy/dx
1/x+1/y*dy/dx=1+dy/dx
（y-1)/y*dy/dx=1/x-1=(1-x)/x
dy/dx=(y-xy)/(xy-x)
一樣的請(qǐng)問(wèn)下：將e^(x+y)換成xy，即dy/dx=[y-xy]/[xy-x]

這個(gè)e^(x+y)怎么換成xy?已知呀xy=e^(x+y)