中国最后通牒

∫[0-(-∞)]xe^(-x^2)dx求教……… 线性代数两个矩阵的列数相同行数不同怎么会行向量组等价呢?我在线代的书上,看到的一个结论是如果m行n列的矩阵A与l行n列的矩阵B的行向量组等价,则方程Ax=0与Bx=0同解,我想问这两个矩阵的 如图,用篱笆靠围一个梯形,篱笆总长23米梯形的面积是多少米? （线性代数）同维同个数向量组A,b等价能否推出其组成矩阵(m*n)列等价?m维列向量组a1,a2……an,与m维列向量组b1,b2……bn等价,前一组组成矩阵A,后一组组成矩阵B,是否能推出矩阵A列等价于矩阵B? 国外一尺等于国内多少? 线性代数非齐次方程组同解推出增广矩阵行向量组等价1.“矩阵A与B行等价”是否等价于“A的行向量组与B的行向量组等价”?2.若“非齐次线性方程组Ax=a与Bx=b同解”,可否推出“增广矩阵(A,a) 最强大脑中,中国雨人那一期的背景音乐.1:28秒那里也有,就是和珍珠港的那个音乐交替播放,应该有名字的. 最强大脑国际赛为什么在中国比赛?这对外国选手公平吗?又为什么是在省级电视台? 最强大脑 中国雨人对战德国次方哥谁赢了 迪拜地理位置在哪? 迪拜国际机场的地理位置是在哪里?是属于哪个时区? 迪拜的准确地理位置 迪拜的地理位置?迪拜具体在那个国家,与哪些国家相邻?它的经纬度是多少?民族风情与我们有什么不同?哪些地方好玩?旅游大概价位是多少? 迪拜 迪拜在世界地图上的位置? 如何巧记中国各省份地理位置 有什么办法能把中国各个省的地图形状记下来 设实矩阵A是正定矩阵,证明：对于任意正整数 Ak也是正定矩阵 日本地震 据我估计日本地震还会不停的发生 日本即将在地图上消失. They were in his pocket.的肯、否定句回答?快点~~~~~~~~~~~有悬赏啊~~~~~~~~~~~~~ 求∫xe^（x^2）dx的不定积分要过程,详细滴,thanks They were in his pocket.改为否定句一般疑问句肯定回答否定回答 求不定积分∫xe*x dx 是e的x次方. 句型转换：they were in his pocket(同上）su hai took same photos at the sports day.nancy went to school early.we sang some english songs.they played football in the playgtound.同义 they were here yesterday变否定句和疑问句 They were at work at that time.（改为否定句和一般疑问句并作肯否定回答） 矩阵Am*n的秩为r,则AX=0的基础解系一定由（）个线性无关的解向量构成.本人线性代数的基础不是太好，最好请达人们提供一些相关的概念有助于我的理解 利用房屋墙壁用三面篱笆围成一个梯形菜地.已知篱笆的长是80米求这块地的面积.（高是20米） Were they talking loudly,or were they talking quietly?应该怎么回答? they were talking loudly是主谓宾吗 为什么 they were talking loudly when the teacher came in”when the teacher came in “划线对划线部分提问_________ _______ they talking loudly? The bus left.They were talking happily.(合并为一句)The bus left.They were talking happily.(合并为一句)The bus left _____ they were talking happily They were talking ( ) a film when come ( ) the room