先化简，后求值： 2xy2−[3xy−(2xy−3xy2)] ，其中 x=−12,y=2 ._刷题宝

题干

先化简，后求值： 2xy2−[3xy−(2xy−3xy2)] ，其中 x=−

1

2

,y=2 .

上一题下一题 0.0难度选择题更新时间:2016-01-30 03:32:06

答案(点此获取答案解析）

解：原式

= 2 x y^{2} - (3 x y - 2 x y + 3 x

同类题1

2015年2月16日，四川省副省长、省食安委副主任陈文华率食品药品监管部门到资阳市检查春节前食品安全工作，突出对节日消费量大、消费者申诉举报多以及群众日常生活必需品等重点区域、重点品种的监督检查。材料表明政府（）

①坚持对人民负责的原则、为人民服务的宗旨②履行组织社会主义经济建设的职能

③履行社会建设的职能④履行政治职能，以达到树立政府威信，提高政府公信力的目的

同类题2

根据对话情景，填入恰当的单词。

Mr. Brown: Good morning. My name is Edward Brown. I'm your new ____, and I moved in yesterday.

Mrs. Smith: Good morning, Mr. Brown. May I help you?

Mr. Brown: I'm trying to do some work now. But I'm afraid your children are making too much ____.

Mrs. Smith: Oh, I'm sorry, Mr. Brown. But you know it's____ to keep little boys quiet.

Mr. Brown: But I can't stand it any more. I couldn't work and I couldn't ____ at all last night.

Mrs. Smith: I'm very, very sorry. I'll do my best to keep them quiet. But I'm not sure it'll work.

Mr. Brown: Well, it seems I have to put up with it now.

Mrs. Smith: Don't ____. My husband will come back from business tonight. And the boys always listen to him.

同类题3

下列词语中字形完全正确的一项是（）

同类题4

—What did Tina say?
—Sorry, I didn't ________ what she said.

同类题5

如图所示，倾角为θ的斜面固定在地面，质量为m的物体，在沿斜面方向的恒力F作用下，沿粗糙的斜面匀速地由A点运动到B点，动摩擦因素为μ，物体上升的高度为h。则在运动过程中:

小学学科试题库

初中学科试题库

高中学科试题库