7)己知 (3/4a)=(4/5b)=(5/7c)，其中a,b及 c 均為正數。下列何者正確？
A. b>a>c
B. b>c>a
C. c>a>b
D. c>b>a
數學 比和率 急！！?
2017-07-21 6:28 pm
回答 (2)
2017-07-21 7:24 pm
Let z=3/4, 4/5, 5/7,
z大些引起a小些, for a>0
ANS=C.
z大些引起a小些, for a>0
ANS=C.
2017-07-21 6:34 pm
Sol
(3/4a)=(4/5b)=(5/7c)
(4a/3)=(5b/4)=(7c/5)
(4a/3)=(5b/4)=(7c/5)
(4a/3)/140=(5b/4)/140=(7c/5)/140
a/105=b/112=c/100
b>a>c
(3/4a)=(4/5b)=(5/7c)
(4a/3)=(5b/4)=(7c/5)
(4a/3)=(5b/4)=(7c/5)
(4a/3)/140=(5b/4)/140=(7c/5)/140
a/105=b/112=c/100
b>a>c
收錄日期: 2021-05-01 15:45:04
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20170721102849AArGJkr