document.write( "Question 486794: Working together, two men can do a job in 20 days. Working alone, however, it would take one man 9 days longer than it would take the other to complete the job. How long would it take each separately? \n" ); document.write( "
Algebra.Com's Answer #333030 by ankor@dixie-net.com(22740)![]() ![]() You can put this solution on YOUR website! Working together, two men can do a job in 20 days. \n" ); document.write( "Working alone, however, it would take one man 9 days longer than it would take the other to complete the job. \n" ); document.write( " How long would it take each separately? \n" ); document.write( ": \n" ); document.write( "Let t = time required by the 1st man to do the job alone \n" ); document.write( "then \n" ); document.write( "(t+9) = time required by the 2nd man alone \n" ); document.write( ": \n" ); document.write( "Let the completed job = 1 \n" ); document.write( ": \n" ); document.write( "A typical shared work equation \n" ); document.write( ": \n" ); document.write( "Each man will do a fraction of the job, the two fractions add up to 1 \n" ); document.write( ": \n" ); document.write( " \n" ); document.write( ": \n" ); document.write( "multiply by t(t+9), results \n" ); document.write( "20(t+9) + 20t = t(t+9) \n" ); document.write( "20t + 180 + 20t = t^2 + 9t \n" ); document.write( ": \n" ); document.write( "Arrange as a quadratic equation \n" ); document.write( "t^2 + 9t - 40t - 180 = 0 \n" ); document.write( "t^2 - 31t - 180 = 0 \n" ); document.write( ": \n" ); document.write( "you can solve this using the quadratic equation, but it will factor to: \n" ); document.write( "(t-36)(t+5) = 0 \n" ); document.write( ": \n" ); document.write( "the positive solution \n" ); document.write( "t = 36 days required by the 1st man \n" ); document.write( "then \n" ); document.write( "36 + 9 = 45 days required by the 2nd man \n" ); document.write( ": \n" ); document.write( ": \n" ); document.write( "Check this \n" ); document.write( "20/36 + 20/45 \n" ); document.write( ".56 + .44 = 1 \n" ); document.write( " \n" ); document.write( " |