I have the following equations, which is supposed to be correct, it was given by our teacher:
But while I can see where the first part comes from perfectly well, I just don't know where did she get that summation from and the final result...
I have the following equations, which is supposed to be correct, it was given by our teacher:
But while I can see where the first part comes from perfectly well, I just don't know where did she get that summation from and the final result...