$11x^{6\ }and\ 11x^3$  

 $-7x^2y\ \ and\ \ \ \frac{1}{2}\ x^2y\ _{ }$  

 $\frac{4}{x}\ \ and\ \ \frac{1}{x}$  

 $6x^2y^3z^4\ \ \ \ and\ \ \ 5\ y^3\ z^4\ a^2$