document.write( "Question 1062603: find the value of x if: log5 + log(x+2) - log(x-1) = 2 \n" ); document.write( "
Algebra.Com's Answer #677561 by Theo(13342)![]() ![]() You can put this solution on YOUR website! start with:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "log(5) + log(x+2) - log(x-1) = 2\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "subtract log(5) from both sides to get:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "log(x+2) - log(x-1) = 2 - log(5)\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "since log(2) = 100, this becomes:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "log(x+2) - log(x-1) = log(100) - log(5)\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "this is equivalent to:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "log((x+2)/(x-1)) = log(100/5) which is equal to:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "log((x+2)/(x-1)) = log(20)\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "this is true if and only if (x+2)/(x-1) = 20\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "solve for x to get x = 22/19.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "replace x with 22/19 in your original equation and you will see that the equation is true.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "you will get log(5) + log(60/19) - log(3/19) = 2\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "evaluate this using your calculator to get 2 = 2.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "this confirms your solution is correct.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "your solution is x = 22/19.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \n" ); document.write( " |