Inequality

👨🏻‍🏫 學術台數學

[匿名]

2012-11-10 5:50 am

a, b, c and d are 4 positive integers. If a/b > c/d. Is it true that ac > bd ? Please prove your answer.

回答 (3)

螞蟻雄兵

2012-11-10 7:01 am

✔ 最佳答案

a，b，c and d are 4 positive integers. If a/b>c/d.Is it true that ac>bd ? Please prove
your answer.
Sol
a=3，b=4，c=1，d=2
3/4>1/2
ac=3，bd=8
3<8
false

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用戶38102

2012-11-10 9:59 pm

a=3，b=4，c=1，d=2
3/4>1/2
ac=3，bd=8
3<8
It is not true

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一個青檸

2012-11-10 5:52 am

a/b > c/d
ad > bc
acd^2 > bc^2d
(ac)(d^2) > (bd)(c^2)

If d > c, ac > bd; If d < c, ac < bd.

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