Question

设y=f(x-y)其中f可导且f'≠1则dy/dx=?

Answer 1

y=f(x-y)

dy/dx=f'(x-y)*d(x-y)

=f'(x-y)*(1-dy/dx)

=f'(x-y)-f'(x-y)*dy/dx

[1+f'(x-y)]dy/dx=f'(x-y)

dy/dx=f'(x-y)/[1+f'(x-y)]