document.write( "Question 472890: solve the equation
\n" ); document.write( "log2(x+2)+log2(x-4)=4\r
\n" ); document.write( "\n" ); document.write( "Thanks,
\n" ); document.write( "Nikky \n" ); document.write( "

Algebra.Com's Answer #324225 by ankor@dixie-net.com(22740) $\"\"$ $\"About$

You can put this solution on YOUR website!
solve the equation
\n" ); document.write( "log2(x+2) + log2(x-4) = 4
\n" ); document.write( "Same as:
\n" ); document.write( " $\"log2%28%28x%2B2%29%2A%28x-4%29%29\"$ = 4
\n" ); document.write( "FOIL
\n" ); document.write( " $\"log2%28x%5E2-2x-8%29\"$ = 4
\n" ); document.write( "exponent equiv of logs
\n" ); document.write( "x^2 - 2x - 8 = 2^4
\n" ); document.write( ":
\n" ); document.write( "x^2 - 2x - 8 = 16
\n" ); document.write( ":
\n" ); document.write( "x^2 - 2x - 8 - 16 = 0
\n" ); document.write( ":
\n" ); document.write( "x^2 - 2x - 24 = 0
\n" ); document.write( "Factors to
\n" ); document.write( "(x-6)(x+4) = 0
\n" ); document.write( "Two solutions
\n" ); document.write( "x = 6
\n" ); document.write( "x = -4
\n" ); document.write( ":
\n" ); document.write( "x = 6 is the only solution to the original equation (can't have the log of a neg) \n" ); document.write( "

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