In algebra there is a method for factoring polynomials
called "guess and check."
You figure out the factors A and C  
and mix and match them until you find something equal to the original problem.
It's a good analogy for this feeling, these moments, where a direct answer escapes me, or you.
So I am left with no other method,
besides "guess and check."
Sometimes the first few guesses find the answers, sometimes you have to try it twenty different ways.

I am exhausted by this constant guess,
of what A and C equal.
An onerous search for the variables to solve the equation of making you happy.