(-a^5)除(-a) =a^4
(-m^5)除(-m)^2 =-m^3
(ab)^4除(ab)^2 =(ab)^2
x^n+3除x^n+1 =x^2
(-x)^n+3除(-x)^n+1 =x^2
(y^3)^4除(y^3乘y^2)^2=y^2