$$\frac { x ^ { m + n + 2 } \times x ^ { m + a + 2 } } { x ^ { 2 ( m + a + 1 ) } } = x ^ { 2 }$$
$\left\{\begin{matrix}a=n\text{, }&\left(x\neq -1\text{ and }Denominator(m+n)\text{bmod}2=1\text{ and }Denominator(2m+2n)\text{bmod}2=1\text{ and }x<0\right)\text{ or }\left(x\neq 1\text{ and }x>0\right)\\a\in \mathrm{R}\text{, }&x=1\end{matrix}\right.$
