Can anyone explain what&#x27;s meant by this?<p>&gt; Multiplying by x^(n+2) and summing over all n, we get<p>Is n the iterating variable, or the domain?  What are the possible values of n?  Wouldn&#x27;t &quot;all&quot; values (whichever set that may be) give an infinite sum?  I thought that infinite expressions did not obey the same laws as finite ones, and couldn&#x27;t be generally used with algebraic transformations.<p>I guess I don&#x27;t know as much math as I thought.