document.write( "Question 477001: Joel drives his car for 20 km at a certain speed. At a distance,he increases his speed by 5 km per hour and drives for an additional 20 km. If the total trip taken is 1 hour, what is his original speed?
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Algebra.Com's Answer #327165 by ankor@dixie-net.com(22740)\"\" \"About 
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Joel drives his car for 20 km at a certain speed.
\n" ); document.write( " At a distance, he increases his speed by 5 km per hour and drives for an additional 20 km.
\n" ); document.write( " If the total trip taken is 1 hour, what is his original speed?
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\n" ); document.write( "Let s = his original speed
\n" ); document.write( "then
\n" ); document.write( "(s+5) = his faster speed
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\n" ); document.write( "Write a time equation, time = dist/speed
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\n" ); document.write( "Time at original speed + time at faster speed = 1 hr
\n" ); document.write( "\"20%2Fs\" + \"20%2F%28%28s%2B5%29%29\" = 1
\n" ); document.write( "multiply by s(s+5) to get rid of the denominators, results:
\n" ); document.write( "20(s+5) + 20s = s(s+5)
\n" ); document.write( "20s + 100 + 20s = s^2 + 5s
\n" ); document.write( "40s + 100 = s^2 + 5s
\n" ); document.write( "combine on the right to form a quadratic equation
\n" ); document.write( "0 = s^2 + 5s - 40s - 100
\n" ); document.write( "s^2 - 35s - 100 = 0
\n" ); document.write( "Solve this equation using the quadratic formula
\n" ); document.write( "\"s+=+%28-%28-35%29+%2B-+sqrt%28-35%5E2-4%2A1%2A-100+%29%29%2F%282%2A1%29+\"
\n" ); document.write( "the positive solution is what you want here, check your solution in the original equation. \n" ); document.write( "
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