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求四阶行列式1234/2341/3412/4123要有过程和方法！结果无所谓 与四阶行列式（1234）（5678)（0010）（9876）的值相等的三阶行列式是, 四阶行列式 第一行 1234 第二行-1234 -1-234 -1-2-34 请问四阶行列式第一行1234第二行2341第三行3412第四行4123 怎么计算 1.The old woman kept one black dog and two white__________.A.one B.ones C.those D.one's2.Henry___________ be at home because he phoned me from the farm just now.A.mustn't B.isn't able to C.may not D.can't3.____________ India and China are of_________ can i get you a drink?it's really nice of you.but i have got____.A.this B.that C.it D.one A和D为什么选D 这是我疑问的地方 1,（）cool story it isA.what B what a C how D how a2,he always works ()a careleaa wayAin B on C by D with3,the watch i lost yesterday ()in the desk A has found B found C has been found D is found4,Columbus () AMERICA in 1492A find B find out Cinven 三角+三角+三角-方块-方块=12 方块+方块+方块-三角-三角=2 问三角 和 方块 =多少? 已知a,b,c是三角形ABC的三边,若a,b,c的倒数成等差数列,求证角B为锐角.2/b=1/a+1/c2/sinB=1/sinA+1/sinC2/sinB=(sinA+sinC)/sinAsinC所以sinAsinC=-(1/2)[cos(A+C)-cos(A-C)]＞0cos(A+C)-cos(A-C)＜0-cosB-cos(A-C)＜0cosB＞cos(C-A)∵1/ 已知a,b,c是三角形ABC的三边,若a,b,c的倒数成等差数列,求证角B是锐角 已知3的X+2的平方*5的X+2的平方=15的3X-4 1.The price of cell phones _____ recently .A have risen B has been raised C has raised D has lifted2.The next plane ______ is from England.A arriving B to arrive C reaching D to reach3.I'd like to know if it will ______ if I park my car here.A mind B 请教几道初中英语题.要详细解释谢谢!1、 ? the shop ? in the morning? A.Is ,close B.Does , opened C.Does ,closed D.Is ,open 2、 ? begin at 8:00. A.The class B. A class C.Class D. Classes 1：Class3 won the football match!____it be ture?a;May b;Must C;Will D;Can2：____ I have your name?Yes,Smith.S-M-I-T-Ha:must b:may c:will d:need3:Will you ____ finish your homework before 8 o'clock this evening?a:can b:may c:be able to d:able to4:Ei 1.I will wait for Tim ___ he gets back.(答案是as,为什么till不行)A.that B.asC.till D.when2.Although it was so cold ,___ he went out without an overcoat.（答案是C,为毛啊）A.but B.soC.yet D.and3.He's already back to Australia,____?（答 1、How has it been ______there in the last five years?a.working on b.going on c.depending on 2.The fighting_______for a week.a.going on b.continued c,away from 3.He is not from the south._______am I.我觉得是so可答案是nor,为什么? 三角形ABC的三边a,b,c的倒数成等差数列,求证B>π/2度 三角形ABC的三边a,b,c的倒数成等差数列,求证B 在三角形ABC中,角A,角B,∠C的对边分别为a,b,c,若a,b,c三边的倒数成等差数列,求证,∠B 方框方框圆圈+圆圈方框圆圈=1三角形70(相同的图形表示相同的数字) 三角形＝圆＋圆＋圆,三角形＋圆形＝40,圆＝?,三角形＝? x-1分之2+ 2+3x分之1=3x平方-x-2分之3的解 三角形ABC的三边长abc的倒数成等差数列求证B 翻译 1)He exercised until his body cried for a rest.2)Don't let the high prices keep you from starting a collection of your own.为什么是let us not play 而不是let us don't play _____exciting news you've given us!A.What B.What an C.What a D.HOW答案上是A,但为什么不是B呢,I always get up late ______Sunday mornings.A.in B.on C.at D.from.这里答案上是B,不是说有日期才用on吗.为什么直接就用On了. 1/2+1/4+1/8+1/16+1/32的简便算法. △ABC的三边a b c的倒数成等差数列,求证B＜π/2.用反证法证明 什么是通货比/平方根法则/货币乘数 吸引金钱法则是什么? 货币时间价值公式怎么记?老是混掉,感觉都没不是很清楚公式的内在意思,有什么规律可以帮助记忆吗? 如图,三角形ABC的三个顶点都在圆O上,且AB=AC=13,BC=24,求圆的半径 24个圆圈和1个三角形的图形,不经三角形连接所有圆圈,不可用斜线圆 圆 圆 圆 圆圆 圆 圆 圆 圆圆 圆 圆 圆 圆圆 圆 圆 圆 三圆 圆 圆 圆 圆圆就是圆形,三就是三角形,不经过三角形将所有圆形