Consider $6a^{2}+35ab-6b^{2}$ as a polynomial over variable $a$.
$$6a^{2}+35ba-6b^{2}$$
Find one factor of the form $ka^{m}+n$, where $ka^{m}$ divides the monomial with the highest power $6a^{2}$ and $n$ divides the constant factor $-6b^{2}$. One such factor is $6a-b$. Factor the polynomial by dividing it by this factor.
