Consider $Iu^{4}+v^{2}u^{3}$ as a polynomial over variable $u$.
$$Iu^{4}+v^{2}u^{3}$$
Find one factor of the form $Iu^{k}+m$, where $Iu^{k}$ divides the monomial with the highest power $Iu^{4}$ and $m$ divides the constant factor $v^{2}u^{3}$. One such factor is $Iu+v^{2}$. Factor the polynomial by dividing it by this factor.
