Given a square (n by n) matrix **A** and a number x, we can form **A**^{2},
or 5**I**_{n }+ 7**A **+ **A**^{2} or even **I**_{n
}+ (x**A**) + (x**A**)^{2 }+ (x**A**)^{3 }+
... which we can identify with (**I**_{n} - x**A**)^{-1},
if it exists.

To see this multiply it by **I**_{n} - x**A**. If the series converges
you get **I**_{n}.