Proof of something..... I posted this in the calculus section...but no reply... I came across this while studying the most general noether's theorem which I will later apply to quantum field theory. So I am posting this here, hoping that some one would have come across this while studying qft I was learning noether's theorem and I came up with something that I can't seem to prove. Prove - [tex] d (\delta x) = \delta (d x)[/tex] I was trying to prove the more general expression [tex] d (\delta f) = \delta (d f)[/tex] where f( x, y, z, t, .....) is a function of n variables. If i could prove the first then the second is proved....any help?