document.write( "Question 738480: Solve the logarithmic equation.
\n" ); document.write( "log x + log(x + 48) = 2
\n" ); document.write( " \n" ); document.write( "

Algebra.Com's Answer #450828 by josmiceli(19441) $\"\"$ $\"About$

You can put this solution on YOUR website!
The key is to make the substitution
\n" ); document.write( " $\"+2+=+log%28+100+%29+\"$
\n" ); document.write( " $\"+log%28x%29+%2B+log%28+x+%2B+48+%29+=+log%28+100+%29+\"$
\n" ); document.write( " $\"+log%28+x%2A%28+x+%2B+48+%29+%29+=+log%28+100+%29+\"$
\n" ); document.write( " $\"+x%5E2+%2B+48x+-+100+=+0+\"$
\n" ); document.write( " $\"+%28+x+%2B+50+%29%2A%28+x+-+2+%29+=+0+\"$ ( by inspection )
\n" ); document.write( " $\"+x+=+-50+\"$ ( disregard )
\n" ); document.write( " $\"+x+=+2+\"$
\n" ); document.write( "-----------
\n" ); document.write( "Check:
\n" ); document.write( " $\"+log%28x%29+%2B+log%28+x+%2B+48+%29+=+log%28+100+%29+\"$
\n" ); document.write( " $\"+log%282%29+%2B+log%28+2+%2B+48+%29+=+log%28+100+%29+\"$
\n" ); document.write( " $\"+log%28+2%2A50+%29+=+log%28+100+%29+\"$
\n" ); document.write( " $\"+100+=+100+\"$
\n" ); document.write( "OK
\n" ); document.write( " $\"+x+=+-50+\"$ cannot be an answer because the expession
\n" ); document.write( " $\"+log%28x%29+\"$ would make no sense. There cannot be a log
\n" ); document.write( "which will gives you a negative number.\r
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\n" ); document.write( "\n" ); document.write( " \n" ); document.write( "

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