1﹣a, , 32+42 , , -x3y4, , x2﹣8x+7.
, ,0, , , ,
( 1 )单项式集合:
( 2 )多项式集合:
( 3 )整式集合:
5a2b,- , ,b2-4ac, ,-1,-2xy, ,πr2.