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

题目

-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

答案

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