maths F.1 @ zogfly3的部落格

標題:

maths F.1

發問:

1. if a:b = 2:3, find 5a + 2b over 3a-b 2. Given that 3x =4y and 3y=5z, find x: y: z

最佳解答:

1. a : b = 2 : 3 Let a = 2k and b = 3k [5a + 2b]/[3a - b] = [5(2k) + 2(3k)]/[3(2k) - (3k)] = [10k + 6k]/[6k - 3k] = (16k)/(3k) = 16/3 ===== 2. 3x = 4y x/4 = y/3 x : y = 4 : 3 x : y = 20 : 15 ...... (1) 3y = 5z y/5 = z/3 y : z = 5 : 3 y : z = 15 : 9 ...... (2) Compare (1) and (2): x : y : z = 20 : 15 : 9 =

其他解答:

答案: 1.) =5/1/3 2.) X=170 Y=127.5 Z=102 2008-10-21 23:07:46 補充： Sorry=.= 做錯....... Z應該=76.5