-1/2 ,ab ,a+b ,100x²y² ,-x/8 ,x²-y² ,a²-2a+1 ,2πR

问题描述:

-1/2 ,ab ,a+b ,100x²y² ,-x/8 ,x²-y² ,a²-2a+1 ,2πR
哪些是单项式 哪些是多项式

单项式:-1/2 ,ab ,100x²y² ,-x/8 ,2πR
多项式:a+b ,x²-y² ,a²-2a+1 ,