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標題:

logarithmic qs.

發問:

express x in terms of y 1.1/2 log x = 2 + log y 2. log (x-2y) = 3 thanks 更新: 1) log x = 4 + 2 log y 2) log x = log 10^4 + log y ^2 why1 become 2 ??

最佳解答:

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• 解方程5y-y的二次方=4@1@
• 中文綜合訓練營1.

 

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logarithmic qs. express x in terms of y 1.(1/2) log x = 2 + log y log(x^1/2) = log (100) + log y <------log100 = 2 log(x^1/2) = log (100y)<--------loga + logb = log(a + b),where a,b > 0 x^1/2 = 100y x = (100y)2 2. log (x-2y) = 3 log(x - 2y) = log(1000)<------log(1000) = 3 x - 2y = 1000 x = 2y + 1000

其他解答:

1. log x=4 + 2log y You had a wrong mistake log (x-2y)=3 x-2y=10^3 instead of 10^4 Therefore 1 wouldn't become 2