We can show that

Here {ul,ui} is Lagrange bracket and [ul,uj] is Poisson bracket. Now

The first four terms on R.H.S on multiplication is

But

The first four terms on R.H.S on multiplication is


The last four terms will be

The second term is

since

Similarly the third term will be zero.
Hence R.H.S of equation (1) is

Therefore
