with w(x)=(x-x(0))(x-x(1))...(x-x(n)) prove that

f[x(0),x(1),x(2),..,x(n))]=summation(0,n) (f(x(i))/(derivative(w(x(i))))

and hence calculate the limit for formula f[x(0),x(1),x(2),..,x(n))] when x(2)->x(1) while all other points remain fixed

i have done the first part but stuck in the second part of calculating the limit.please help

note:f[x(0),x(1),x(2),..,x(n))] is the newton forward difference function