If 7^x = 3^y, which of the following must NOT be correct where x≧0 and y≧0?
(1) x/y = log3 / log7
(2) xy = log(3/7)
(3) x-y = 0
請附解釋...THX
F.4 logarithmic functions1
2010-04-19 6:08 am
回答 (1)
2010-04-20 2:32 am
✔ 最佳答案
7^x = 3^yxlog7=ylog3
x/y = log3/log7
(1) must be correct
if xy=log(3/7)
xy=-0.367976
but x≧0 and y≧0
xy≧0
(2) must not be correct
if x-y =0
x=y
x≧0 and y≧0
(3) may be correct
so,the anwser is (2)
參考: me
收錄日期: 2021-04-13 17:12:16
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