令t=x+y
y=t-x
dy=d(t-x)
d(t-x)/dx=t^2
dt/dx-1=t^2
dt/dx=t^2+1
dt/(t^2+1)=dx
arctant=x+c
arctan(x+y)=x+c
所以正确答案应该是:
arctan(x+y)=x+c
令t=x+y
y=t-x
dy=d(t-x)
d(t-x)/dx=t^2
dt/dx-1=t^2
dt/dx=t^2+1
dt/(t^2+1)=dx
arctant=x+c
arctan(x+y)=x+c
所以正确答案应该是:
arctan(x+y)=x+c