Maths!!!

2008-01-01 7:38 am

已知9^x /3^y =m/n ,試以m、n和y表示x。

A [m(3^y)]/(nlog9)
B (ylogm)/(logn)
C 1/2 [(logm-logn)/log3 +y ]
D (m+3^y)/n
E m(3^y) -n

更新1:

要步驟

回答 (3)

2008-01-01 7:43 am

✔ 最佳答案

9^x /3^y =m/n
3^(2x-y)=m/n
(2x-y)log3=log(m/n)
(2x-y)log3=logm-logn
2x-y=(logm-logn)/log3
∴x=1/2 [(logm-logn)/log3 +y ]
C is the answer

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2008-01-01 7:54 am

answer is C
9^x/3^y=m/n
3^(2x-y)=m/n
log3^(2x-y)=log(m/n)
(2x-y)log3=logm-logn
y=1/2 [(logm-logn)/log3 +y ]

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2008-01-01 7:49 am

The correct answer is C
9^x/3^y=m/n
3^(2x-y)=m/n
log3^(2x-y)=log(m/n)
(2x-y)log3=logm-logn
y=1/2 [(logm-logn)/log3 +y ]

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