已知实数x，y满足约束条件y≥3x-3,2y≤x+4,3x+4y+12≥0.则z=2x-y的最大值为

一篇关于夏令营的作文或日记.200字 2010你最给力的事是什么? 2010最给力 ‘给力’究竟是个啥意思? 只要做四小题 初三数学.第九小题. Finally,study hard .Although we may not get the one prise ,our parents will be very happy.意思? 求孝道的感悟文章? 还有一个月,英语六级应该怎么复习啊?我四级考了三次才过,最后一次考了495. 英语八大时态详解 That duck is swimming slowly.It is looking ( ) something to eat.A、to B、forC、out What season is it?Where's Mother Duck?中文 这个评论是什么意思,每天对话是什么意思?如图, 歌词里有 some like it hot and some aweat when the heat is on 的歌叫什么呀?是 52分44秒的歌 感觉很好听 At (),we get red packets from our parents or grand-parents.填节日名称 Our fingerprints never fades from the lives we We__(not,hear)from our parents for nearly a year.填什么3Q 一道难题,已知xyz=1求x／（xy+x+1）+y／（yz+y+1）+z／（zx+z+1）的值 The soup is too cold.It requires ____.A.to heatB.heatingC./D./为啥选B? 高一一句英语句子改错求帮助I not only like French,but also I am good at it.So does Betty.这句话改错 【根据首字母提示填空】The soup is h---,you can drink it later. 单句改错英语高一Do you know the young man whom has been chosep chaiman?This is the only book that were borrowed from the library.The watch that Monther bought it for me works very well.He left me the book,that is very useful for me. The soup bowl___.___it____yesterday?A.was broken,Was droken B.is broken,Was brokenC.was broken,Did break D.is broken ,Has broken为什么选D?为什么用现在完成时? 英语单句改错（高一）1.The girl dare to go home alone at night.2.You should get a nice gift if you do as I tell you.3.—Look,it must be our teacher.—No,it mustn't be him.He has gone abroad 当-1≤x≤2时 求函数y=-x的平方+2ax+1最大值当-1≤x≤2时 求函数y=-x的平方+2ax+1最大值 这是一道高中数学函数题,写不出来啊, 幸福终点站 THE TERMINAL怎么样 THE TERMINAL CAFé怎么样 Terminal 2 on the 4th 什么意思 已知梯形ABCD中,角A,角B的平分线相交于E,角C,角D平分线交于F,求证：EF//BC 初二数学梯形在梯形ABCD中,AB平行CD,∠A+∠B=90°,E、F分别是AB、CD的中点.求证EF=1/2（AB-CD） 已知梯形ABCD的周长为40cm,上底CD=6cm,DE‖BC交AB于E,则△ADE的周长为____. 在梯形ABCD中,∠ABC=90°,AB=14cm,AD=18cm,BC=21cm,点P从点A开始沿AD边向点D以1cm/s的速度移动,点Q从点C开始沿CB向点B以2cm/s的速度移动,如果点P,Q分别从两点同时出发,问多少秒后（1）以P,B,Q,D为顶点的四