7: The only possible algebraic approach calls for writing this expression
as a product of two equal expressions that can be expanded using
the geometric expansion, but a product of series is something we try to
avoid. This brings one to consider other ways of linking functions. When
differentiated, the given expression is even further from what we know.
However, when integrated, it leads directly to an expression that we know
how to expand. In other words, the given expression is a derivative of
something that can be expanded. Rewrite this something to fit the
geometric series and so that it features