问题 解答题
计算
(1)(9x2+2x+y)-(5x2+2x-y)
(2)(
1
2
mn+n2)×(-2m2
答案

(1)原式=9x2+2x+y-5x2-2x+y

=4x2+2y;

(2)原式=

1
2
mn×(-2m2)+n2×(-2m2

=-m3n-2m2n2

单项选择题
单项选择题