document.write( "Question 441191: A car travels 200 miles. A second car travels 10 mph faster than the first car makes the same trip in one hour less time. Find the speed of each car. \n" ); document.write( "
Algebra.Com's Answer #304606 by htmentor(1343)\"\" \"About 
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Let v = the speed of car 1
\n" ); document.write( "Then v+10 = the speed of car 2
\n" ); document.write( "Let t = the travel time of car 1
\n" ); document.write( "Then t-1 = the travel time of car 2
\n" ); document.write( "Since speed = distance/time, for car 1 we can write:
\n" ); document.write( "v = 200/t [1]
\n" ); document.write( "And for car 2:
\n" ); document.write( "v + 10 = 200/(t - 1)
\n" ); document.write( "And since t = 200/v from equation [1], we have
\n" ); document.write( "v + 10 = 200/(200/v - 1)
\n" ); document.write( "Cross-multiply and solve for v:
\n" ); document.write( "(200/v - 1)(v + 10) = 200
\n" ); document.write( "Using FOIL we get
\n" ); document.write( "200 + 2000/v - v - 10 = 200
\n" ); document.write( "2000/v - v - 10 = 0
\n" ); document.write( "Multiply through by v:
\n" ); document.write( "2000 - v^2 - 10v = 0
\n" ); document.write( "Solve using quadratic formula:
\n" ); document.write( "v = (10 +- sqrt(100 + 8000))/-2
\n" ); document.write( "Take the positive solution:
\n" ); document.write( "v = 40
\n" ); document.write( "So the speed of car 1 is 40 mph; the speed of car 2 is 50 mph \n" ); document.write( "
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