  By introducing the generalized master function of order up to four together
with corresponding weight function, we have obtained all quasi-exactly solvable
second order differential equations. It is shown that these differntial
equations have solutions of polynomial type with factorziation properties, that
is polynomial solutions Pm(E) can be factorized in terms of polynomial Pn(E)
for m not equal to n. All known quasi-exactly quantum solvable models can be
obtained from these differential equations, where roots of polynomial Pn(E) are
corresponding eigen-values.
