document.write( "Question 356937: Engine pulls train 140 miles, 2nd engine is 5 mph faster than first, takes over and pull the train 200 miles, total time required for 6 hrs. \r
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document.write( "find the average rate of each engine. \r
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document.write( "totally stuck on the setup of the problem.. \n" );
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Algebra.Com's Answer #254881 by ankor@dixie-net.com(22740)![]() ![]() You can put this solution on YOUR website! Engine pulls train 140 miles, \n" ); document.write( " 2nd engine is 5 mph faster than first, takes over and pull the train 200 miles, \n" ); document.write( " total time required for 6 hrs. \n" ); document.write( "find the average rate of each engine. \n" ); document.write( ": \n" ); document.write( "Let s = speed of the slower engine \n" ); document.write( "then \n" ); document.write( "(s+5) = speed of the faster \n" ); document.write( ": \n" ); document.write( "Write a time equation, Time = dist/speed \n" ); document.write( ": \n" ); document.write( "Slow engine time + fast engine time = 6 hrs \n" ); document.write( " \n" ); document.write( "multiply by s(s+5), results \n" ); document.write( "140(s+5) + 200s = 6s(s+5) \n" ); document.write( ": \n" ); document.write( "140s + 700 + 200s = 6s^2 + 30s \n" ); document.write( "Arrange as a quadratic on the right \n" ); document.write( "0 = 6s^2 + 30s - 140s - 200s - 700 \n" ); document.write( "6s^2 - 310s - 700 = 0 \n" ); document.write( "Simplify, divide by 2 \n" ); document.write( "3s^2 - 155s - 350 = 0 \n" ); document.write( "Use the quadratic formula to find the positive solution \n" ); document.write( " \n" ); document.write( ": \n" ); document.write( " \n" ); document.write( " |