3a=5 5b=7 7c=9 a*b*c=??

3^a=5 log(3^a)=log5 alog3=log5 a=log5/log3 5^b=7 log(5^a)=log7 alog5=log7 a=log7/log5 7^a=9 log(7^a)=log9 alog7=log9 a=log9/log7 abc=(log5/log3)(log7/log5)(log9/log7) =log9/log3 =log(3²)/log3 =2log3/log3 =2

a = log5/log3
b = log7/log5
c = log9/log7a*b*c = log5/log3 * log7/log5 * log9/log7 = 2

3a=5，5b=7，7c=9，a*b*c=??
Sol
a*b*c
=(3a)*(5b)*(7c)/(3*5*7)
=5*7*9/(3*5*7)
=3

大大你好

3a=5 5b=7 7c=9 a*b*c=??

a=5/3 ,b=7/5 ,c=9/7

5/3*7/5*9/7=3

5/3表示3分之5

因為我不會打

所以我用文字表示

3個數相乘，都會被約分掉

到最後剩下9/3=3

2011-10-23 18:45:45 補充：
大大你好

你可以參考這篇

http://tw.knowledge.yahoo.com/question/question?qid=1611101301646