document.write( "Question 203500: can someone help me with this question
\n" ); document.write( "thanx.\r
\n" ); document.write( "\n" ); document.write( "solve the following equation for x, giving the answer correct to two decimal places\r
\n" ); document.write( "\n" ); document.write( "\"5%5E%28x-2%29=2%5E%28x%2B3%29\"
\n" ); document.write( "this question is from the book Longman Pre-U Text STPM Mathematics S & T Paper 1
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Algebra.Com's Answer #153526 by jsmallt9(3758)\"\" \"About 
You can put this solution on YOUR website!
To solve for x when it is in exponents is to use logarithms. Since we want our answer in decimal form (and not logarithm form) we need to use a logarithm we can get from out calculator (or other computing device). If calculators have any logarithms at all they will most likely have base 10 logarithms and/or natural (base e) logarithms. Either will work and give the correct answer to the problem.

\n" ); document.write( "\"5%5E%28x-2%29=2%5E%28x%2B3%29\"
\n" ); document.write( "Find the log of both sides:
\n" ); document.write( "\"log%28%285%5E%28x-2%29%29%29=log%28%282%5E%28x%2B3%29%29%29\"
\n" ); document.write( "Now we can get x out of the exponents by using the following property of logarithms (which applies to all bases): \"log%28%28a%5Eb%29%29+=+b%2Alog%28%28a%29%29\". Applying this to our logarithms we get:
\n" ); document.write( "\"%28x-2%29%2Alog%28%285%29%29=%28x%2B3%29%2Alog%28%282%29%29\"
\n" ); document.write( "\"%28log%28%285%29%29%29x+-+2log%28%285%29%29+=+%28log%28%282%29%29%29x+%2B+3log%28%282%29%29\"
\n" ); document.write( "We are now in a position to solve for x. We can either
  • replace the logarithms now with decimals and finish the solution with these decimals
  • Or, complete the solution with logarithms and replace them with decimals at the end.

\n" ); document.write( "I will use the second approach. But if you can't understand this, then repalce the logarithm's now and finish the solution using the decimals.
\n" ); document.write( "Subtract \"%28log%28%282%29%29%29x\" from both sides:
\n" ); document.write( "\"%28log%28%285%29%29+-+log%28%282%29%29%29x+-+2log%28%285%29%29+=+3log%28%282%29%29\"
\n" ); document.write( "Add \"2log%28%285%29%29\" to both sides:
\n" ); document.write( "\"%28log%28%285%29%29+-+log%28%282%29%29%29x+=+3log%28%282%29%29+%2B+2log%28%285%29%29\"
\n" ); document.write( "Divide both sides by \"%28log%28%285%29%29+-+log%28%282%29%29%29\":
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\n" ); document.write( "We can get the logarithms above from our calculator:
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\n" ); document.write( "Simplifying gives:
\n" ); document.write( "\"x+=+5.7823539868301501\"
\n" ); document.write( "Rounded to 2 decimal places:
\n" ); document.write( "\"x+=+5.78\"
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