as+someone+put+it

养影怪4068已知S是△ABC所在平面外的一点.D是SC的中点,若向量BD=x(向量AB)+y(向量AC)+z(向量AS)则x+y+z=? -
胥燕风13783488333 ______[答案] 因为S,D,C三点共线 所以BD=tBC+(1-t)BS=t(BA+AS)+(1-t)(BA+AS) =BA+tAC+(1-t)As =-AB+tAC+(1-t)As 而BD=xAB+yAC+zAS 则x=-1,y=t,z=1-t x+y+z=0

养影怪4068如果向量组α1,α2,...αs线性无关,试证:α1,α1+α2,...α1+α2+...+αs线性无关 -
胥燕风13783488333 ______[答案] 设有一组系数使得α1,α1+α2,...α1+α2+...+αs组合为0 就是c1 α1+c2(α1+α2)+...+cs(α1+α2+...+αs)=0 重新按向量组合 得到 (c1+c2+...+cs) α1 + (c2 +c3+...+cs)α2 + ...+cs as =0 也就是 (c1,c2,...,cs)P ( α1,α1,...,as) =0 其中P= 1 1 .1 0 1 .1 0 0 1 ...1 0 0,.,...

养影怪4068项数为偶数2N的等差数列{an},证明:S2n=n(a1+a2n)=~=n(an+an+1)[an与an+1为中间两项】 -
胥燕风13783488333 ______[答案] 项数为偶数,所以都可以配对,共有N对 p,q,r,s为下标,当p+q=r+s时,有ap+aq=ar+as, 所以a1+a2n=a2+a2n-1=…=ak+a(2n-k+1)……=an+an+1,这n对的值都相等 所以S2n=n(a1+a2n)=……n(ak+a(2n-k+1)=……=n(an+an+1) 解毕

养影怪4068编写一个函数:gear( )接受两个int类型的参数并返回一个int类型的值. -
胥燕风13783488333 ______ 用out参数! public int Method(out int i)//方法定义 { i = 44; return 55; } 调用的时候: int i = 0; int j = Method(out i); 最终结果: i=44; j=55;

养影怪4068My+mother+is+always+p - ----+of+me+when+I+get+the+first+place+in+zhe+class中间填甚么
胥燕风13783488333 ______ 横线上填:proud, be proud of 感到自豪当我在班里获得第1的时候,妈妈总是为我感到自豪

养影怪4068根据释义写出相应的单词或短语(初二第一学期)+按要求该写句子一.1._________someone you write a letter to as a hobby(有人写了一封信,作为一个业余... -
胥燕风13783488333 ______[答案] 1,penfriend 2,hobby 3,how long

养影怪4068英语连接句子,帮帮忙、速度+fen.11.Someone knocked at the door.I went over to answer the door.(用and连接句子2.He is feeling better today .He took some... -
胥燕风13783488333 ______[答案] Someone knocked at the door and then I went over to answer the doorHe is feeling better today because he took some medicine yesterdayhe thinks that Chinese is as important as maths,

养影怪4068P varies inversely as (m+1),when p=4,m=8,find the value of p when m=11.再现等~ -
胥燕风13783488333 ______[答案] p*(m+1)=常数=4*(8+1)=36 p=36/(m+1)=36/(11+1)=36/12=3------when m=11,p=3

养影怪4068帮忙把Helen will have someone to alter that dress to fit her 变成have + object +p.p. 的结构谢谢啊 -
胥燕风13783488333 ______[答案] Helen will have that dress altered to fit her

养影怪4068Look!The computer is - ----(turn)on by someone. -
胥燕风13783488333 ______ turnned看,电脑被人打开了!