document.write( "Question 600979: During the first part of a trip, a canoeist travels 45 miles at a certain speed. The canoeist travels 20 miles on the second part of the trip at a speed 5 mph slower. The total time for the trip is 2 hrs. What was the speed on each part of the trip?
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document.write( "The speed on the first part of the trip was _______ mph. \n" );
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Algebra.Com's Answer #379598 by ankor@dixie-net.com(22740)![]() ![]() You can put this solution on YOUR website! During the first part of a trip, a canoeist travels 45 miles at a certain speed. \n" ); document.write( " The canoeist travels 20 miles on the second part of the trip at a speed 5 mph slower. \n" ); document.write( " The total time for the trip is 2 hrs. What was the speed on each part of the trip? \n" ); document.write( ": \n" ); document.write( "Let s = speed the first part of the trip \n" ); document.write( "and \n" ); document.write( "(s-5) = speed on the 2nd part \n" ); document.write( ": \n" ); document.write( "Write a time equation: time = dist/speed \n" ); document.write( ": \n" ); document.write( "1st part time + 2nd part time = 2 hrs \n" ); document.write( " \n" ); document.write( "multiply by s(s-5) to clear the denominators, results: \n" ); document.write( "45(s-5) + 20s = 2s(s-5) \n" ); document.write( ": \n" ); document.write( "45s - 225 + 20s = 2s^2 - 10s \n" ); document.write( ": \n" ); document.write( "65s - 225 = 2s^2 - 10s \n" ); document.write( ": \n" ); document.write( "0 = 2s^2 - 10s - 65s + 225 \n" ); document.write( "A quadratic equation \n" ); document.write( "2s^2 - 75s + 225 = 0 \n" ); document.write( "Use the quadratic formula to fins s \n" ); document.write( " \n" ); document.write( "In this equation: x=s; a=2; b=-75; c=225 \n" ); document.write( " \n" ); document.write( ": \n" ); document.write( " \n" ); document.write( ": \n" ); document.write( " \n" ); document.write( "Two solutions, but only this one makes sense. \n" ); document.write( " \n" ); document.write( "s = \n" ); document.write( "s = 34.2 mph on the 1st part of the trip \n" ); document.write( "and \n" ); document.write( "34.2 - 5 = 29.2 mph on the 2nd part \n" ); document.write( ": \n" ); document.write( ": \n" ); document.write( "Let's see if this checks out, find sum of the times at each speed \n" ); document.write( "45/34.2 = 1.3158 hrs at 34.2 mph \n" ); document.write( "20/29.2 = 0.6849 hrs at 29.2 mph \n" ); document.write( "--------------------------------- \n" ); document.write( "tot time: 2.0007 hrs which is the total time \n" ); document.write( " \n" ); document.write( " |