Our task is to simplify expressions of the form
by expressing them in the form
or 
To express in terms of the first, we write,
Remembering now that
are all constants, we can equate the coefficients of
and 
on both sides, to give simultaneous equations:
For
(1) and
(2)
(2)/(1) gives
and 
so
where 
and 
are given as above.
A similar procedure gives, when we want to write,
as 
Example:
Write
in the form
and 
We may also be asked to solve equations such as
As above, we write
and put this equal to 1. We solve
