x^y-y^x=2,求dy/dx

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x^y-y^x=2,求dy/dx

x^y-y^x=2,求dy/dx
x^y-y^x=2,求dy/dx

x^y-y^x=2,求dy/dx
令x^y=u,则:ylnx=lnu,∴lnxdy/dx+y/x=(1/u)du/dx,∴u(lnxdy/dx+y/x)=du/dx,
∴du/dx=x^y·lnx·dy/dx+(y/x)x^y.
令y^x=t,则:xlny=lnt,∴lny+(x/y)dy/dx=(1/t)dt/dx,∴t[lny+(x/y)dy/dx]=dt/dx,
∴dt/dx=y^x·lny+(x/y)y^x·dy/dx.
∵x^y+y^x=2,∴u+t=2,∴du/dx+dt/dx=0,
∴[x^y·lnx·dy/dx+(y/x)x^y]+[y^x·lny+(x/y)y^x·dy/dx]=0,
∴[x^y·lnx+(x/y)y^x]dy/dx=-[(y/x)x^y+y^x·lny],
∴dy/dx=-[(y/x)x^y+y^x·lny]/[x^y·lnx+(x/y)y^x].