document.write( "Question 139174: Please help me translate into a quadratic equation and solve.\r
\n" ); document.write( "\n" ); document.write( "Steve traveled 200 miles at a certain speed. Had he gone 10 MPH faster, the trip would have taken 1 hour less. Find the speed of his vehicle.
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Algebra.Com's Answer #101502 by ankor@dixie-net.com(22740)\"\" \"About 
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Steve traveled 200 miles at a certain speed. Had he gone 10 MPH faster, the trip would have taken 1 hour less. Find the speed of his vehicle.
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\n" ); document.write( "Let s = his actual speed
\n" ); document.write( "then
\n" ); document.write( "(s+10) = his \"if\" speed
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\n" ); document.write( "Write a time equation: Time = dist/speed
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\n" ); document.write( "Actual time = Faster speed time + 1 hr
\n" ); document.write( "\"200%2Fs\" = \"200%2F%28%28s%2B10%29%29\" + 1
\n" ); document.write( "Multiply equation by s(s+10) to get rid of the denominators:
\n" ); document.write( "s(s+10)*\"200%2Fs\" = s(s+10)*\"200%2F%28%28s%2B10%29%29\" + s(s+10)*1
\n" ); document.write( "cancel the denominators out and you have:
\n" ); document.write( "200(s+10) = 200s + s(s+10)
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\n" ); document.write( "200s + 2000 = 200s + s^2 + 10s
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\n" ); document.write( "Combine;
\n" ); document.write( "0 = s^2 + 10s + 200s - 200s - 2000
\n" ); document.write( "A quadratic equation
\n" ); document.write( "s^2 + 10s - 2000 = 0
\n" ); document.write( "Factors to:
\n" ); document.write( "(s+50) (s-40) = 0
\n" ); document.write( "The positive solution:
\n" ); document.write( "s = +40 mph is his speed
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\n" ); document.write( "Check solution by finding the times
\n" ); document.write( "200/40 = 5 hrs
\n" ); document.write( "200/50 = 4 hrs
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