请写出一个次数为2,项数为3,常数项为-1的多项式______.
由于多项式次数为2,即最高项次数为2,
则其余项次数均不高于2,
此多项式为:x2+x-1;yz-x-1;…
不唯一.
Ryan’s family____ very large and his family____all fond of going hiking.
A.is; are
B.are; is
C.is; is
D.are; are
化简m+n-(m-n)的结果为[ ]
A.2m
B.-2m
C.2n
D.-2n