document.write( "Question 383402: how to solve \r
\n" ); document.write( "\n" ); document.write( "3*log7(base 3) without using calculator?\r
\n" ); document.write( "\n" ); document.write( "note : 3*log7(base 3) = log7^3(base 3)
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Algebra.Com's Answer #271537 by jsmallt9(3758)\"\" \"About 
You can put this solution on YOUR website!
I'm guessing you posted this yesterday and I \"solved\" it for you. But I misread the problem and solved something else. Sorry about that!

\n" ); document.write( "If your problem is to find the number for \"3%2Alog%283%2C+%287%29%29\" (or \"log%283%2C+%287%5E3%29%29\" or \"log%283%2C+%28343%29%29\"), without a calculator, then the answer is: It can't be done! (This leads me to suspect that problem may actually be the problem I thought it was yesterday.)

\n" ); document.write( "7 is not a well-known power of 3, 3 is not a well-known power of 7 and both numbers, 3 and 7, are not well-known powers of some other number. One of these would have to be true in order to answer this question without a calculator.

\n" ); document.write( "If the 7 was a 9 instead then we could solve this problem because 9 is a well-known power of 3. Since \"9+=+3%5E2\", \"log%283%2C+%289%29%29+=+2\" and \"3%2Alog%283%2C+%289%29%29+=+3%2A2+=+6\"

\n" ); document.write( "The only thing you can do with your expression is to convert it to an expression of logarithms of a different base. For example, if you did want to use your calculator to find a decimal approximation for the value of your expression, then we could use the base conversion formula for logarithms, \"log%28a%2C+%28p%29%29+=+log%28b%2C+%28p%29%29%2Flog%28b%2C+%28a%29%29\" to convert your base 3 logarithm into a base that your calculator \"knows\" like base 10 or base e (aka ln). Converting your base 3 logarithm into base e logarithms we get:
\n" ); document.write( "\"log%283%2C+%287%29%29+=+ln%287%29%2Fln%283%29\"
\n" ); document.write( "which would make your full expression:
\n" ); document.write( "\"3%2Alog%283%2C+%287%29%29+=+3%2A%28ln%287%29%2Fln%283%29%29\"
\n" ); document.write( "With this we could then use our calculator to obtain a decimal approximation for the value of your expression.
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