Re: [計量求解數學

看板GRE (GRE入學考試)作者Merica (美加文教)時間14年前 (2011/06/13 10:46)推噓0(0推 0噓 0→)

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※ 引述《bonitala (Bonita)》之銘言： : 1.比大小 : (ab)^6=b^-4*c^-8 : columnA:(ab)^9 : columnB:(b^-2*c^-4)^3 : Ans:D Column A是奇數次方，有可能是負值 Column B整理後是偶數次方，必為正值所以Ans：D : 算出來是相等，不知道少考慮到甚麼因素?? : 2.This morning Pat went to the market with a red bag and a greenn one. If : he bought 10 carrots and 6 radishes, in how many ways could he distribute : these vegetable so that no bag would be empty? : Ans:75 : 3.In how many ways can the letters of the word POLLOLOP be arranged? : Ans:560 8個位置中先挑出3個位置放L，剩下5個位置中再挑2個位置放P，剩下的位置自然就是放O 了=C(8,3)．C(5,2)=560 : 4. Ten chair are evenly spaced around a round table and numbered clockwise : from 1 to 10. Five married couple are to sit in the chairs with men and women : alternating, and no one is to sit either next to or directly across from his : or her spouse. How many seating arrangements are possible? : Ans:560 : 我算出來是240..........>< : 只能說我排列組合超爛= =" 答案應是480 假設太太先挑位置，第一位太太有10個位置可挑，因為要男女間隔，第二位太太只剩4個位置可挑，以此類推，第三位太太剩3個位置，第四位剩2個位置，第五位只剩1個位置，等太太坐好，為符合題意，夫妻不相鄰，也不坐在對面，則任何一種太太的坐法，先生的坐法只有2種變化，所以全部坐法=(10x4x3x2x1)x2=480 : 5. what is the greatest integer n such that rs/n is an integer for all : consecutive even integers r and s? : Ans:8 r=2, s=4 n=8 rs/n = 2x4/8 = 1 找r, s最小時能滿足rs/n=integer之最大n值即=8 : 6.when 2/9 of the vote on a certain resolution have been counted,3/4 of those : counted are in favor of the resolution. what fraction of the remaining votes : must be against the resolution so that the total count will result in a vote : of 2 to 1 against the resolution? : Ans:11/14 設剩下的票中要有y反對才能使總票數2：1反對決議案，即y就是答案反對/支持=((2/9x1/4+7/9y) / (2/9x3/4+7/9(1-y))=2/1 解此式即得y=11/14 (以上內容由美加黃冠文老師提供) : 以上，麻煩大家了 : 多謝!! -- ▅▅▅▅ ▅▅ ▅▅▅ ▅ ▅▅ ▅▅▅ █ █ █ █▅ █▄█ ▄ █ █▄█ █ █ █ █▄ █◥▅ █ █▅ █ █ 7/2(六)下午2：00美加文教新制GRE&字彙三合一免費講座莫清崴博士/江璞教授主講歡迎蒞臨 http://www.merica.com.tw/event/20110702/ -- ※ 發信站: 批踢踢實業坊(ptt.cc) ◆ From: 114.36.55.231