標題:
中二數學~上學期--急>
發問:
１.x:y:z=3:4:10因此,Find the value of y if the sum of x, y and z is 51.Ans:___________ ___________ ___________２.(5x) / (4x+6y) - (7x) / (6x+9y) *** [題目中 ( 及 ) 自行加上]Ans:___________ ___________ ___________３.某話劇表演開始時，男觀眾人數與女觀眾人數之比為... 顯示更多 １.x:y:z=3:4:10 因此,Find the value of y if the sum of x, y and z is 51. Ans:___________ ___________ ___________ ２.(5x) / (4x+6y) - (7x) / (6x+9y) *** [題目中 ( 及 ) 自行加上] Ans:___________ ___________ ___________ ３.某話劇表演開始時，男觀眾人數與女觀眾人數之比為 8:9。(最好用英文答) 20分鐘後，遲到的15名男觀眾和8名女觀眾加入觀看該表演，使男觀眾人數與女觀眾人數相等。 (a)求該話劇表演開始時的男觀眾人數與女觀眾人數。 (b)話劇團若干張$100價惠劵，總值為$12 000。話劇團有沒有足夠的$100價惠劵向每名觀眾贈送一張$100價惠劵﹖試解釋你的答案。 ４. a = (2b) / (c) -3 [c] *** [題目中 ( 及 ) 自行加上] 上題要求找回Subjest [c] Ans:___________ ___________ ___________ ５. X = [100(S-C)] / [C] *** [題目中 [ 及 ] 自行加上] 上題要求找回Subjest [C] Ans:___________ ___________ ___________ 感激不盡~~~~~~~~~~~~~~~^^
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最佳解答:
1. x=3w, y=4w, z=10w x+y+z=51 3w+4w+10w=51 17w=51 w=3 so y=4w=12 2. (5x) / (4x+6y) - (7x) / (6x+9y) = (5x) / [2(2x+3y)] - (7x) / [3(2x+3y)] = (5/2-7/3) [x / (2x+3y)] = (15/6 - 14/6) [x / (2x+3y)] = x / [6(2x+3y)] 3(a) Let x and y be the number of male and female attendants to the show when it started respectively. From the question, x : y = 8 : 9, i.e. 9x = 8y -------(1) x + 15 = y + 8 i.e. y = x + 7 -------(2) Substitute (2) into (1), 9x = 8(x+7) x = 56 Substitute x=56 into (2), y = 56+7 = 63 Therefore when the show started, there were 56 male attendants and 63 female attendants. (b) Total number of attendants = 56 + 63 = 119 Number of coupons = 12000 / 100 = 120 > 119 Yes, there are enough coupons for each attendants. 4. a = (2b) / (c) -3 a + 3 = (2b) / c c (a + 3) = 2b c = (2b) / (a + 3) 5. X = [100(S-C)] / [C] XC = 100S - 100C (100+X)C = 100S C = (100S) / (100+X) 2014-01-05 16:48:27 補充： 3(b) correction: 's' deleted Yes, there are enough coupons for each attendant.
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