document.write( "Question 191774This question is from textbook saxon algebra 2
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document.write( ": logx+log(x+1)=log20
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document.write( "x=5
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document.write( "Am I correct? \n" );
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Algebra.Com's Answer #143899 by RAY100(1637)![]() ![]() ![]() You can put this solution on YOUR website! adding logs is multiply\r \n" ); document.write( "\n" ); document.write( "x(x+1) = 20\r \n" ); document.write( "\n" ); document.write( "x^2 +x -20 =0\r \n" ); document.write( "\n" ); document.write( "(x+5) (x-4) =0\r \n" ); document.write( "\n" ); document.write( "x= (-5), (+4) but we need to check\r \n" ); document.write( "\n" ); document.write( "log(4) +log(4+1) = log 20\r \n" ); document.write( "\n" ); document.write( ".602 +.699=1.30 ok therefore x=+4 is valid\r \n" ); document.write( "\n" ); document.write( "however when we start log (-5) etc we find again that there are no logs for negative numbers \n" ); document.write( "therefore x= (-5) is not valid \n" ); document.write( " |