document.write( "Question 242907: Two cars start out at the same point. One car starts out driving north at 25 mph. Two hours later the second car starts driving east at 20 mph. How long after the first car starts traveling does it take the two cars to be 300 miles apart? \n" ); document.write( "
Algebra.Com's Answer #177893 by ankor@dixie-net.com(22740)\"\" \"About 
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Two cars start out at the same point.
\n" ); document.write( " One car starts out driving north at 25 mph.
\n" ); document.write( " Two hours later the second car starts driving east at 20 mph.
\n" ); document.write( "How long after the first car starts traveling does it take the two cars to be 300 miles apart?
\n" ); document.write( ":
\n" ); document.write( "This is pythag problem; a^2 + b^2 = c^2
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\n" ); document.write( "Let t = driving time of 1st car
\n" ); document.write( "then
\n" ); document.write( "25t = distance driven by the 1st car (a)
\n" ); document.write( ":
\n" ); document.write( "Let (t-2) = driving time of 2nd car
\n" ); document.write( "then
\n" ); document.write( "20(t-2) = distance driven by the 2nd car
\n" ); document.write( "Simplify to:
\n" ); document.write( "(20t-40) (b)
\n" ); document.write( ":
\n" ); document.write( "c = 300 mi
\n" ); document.write( ":
\n" ); document.write( "(25t)^2 + (20t-40)^2 = 300^2
\n" ); document.write( "FOIL
\n" ); document.write( "625t^2 + (400t^2 - 1600t + 1600) = 90000
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\n" ); document.write( "625t^2 + 400t^2 - 1600t + 1600 - 90000 = 0
\n" ); document.write( ":
\n" ); document.write( "1025t^2 - 1600t - 88400 = 0
\n" ); document.write( ":
\n" ); document.write( "Simplify, divide by 25
\n" ); document.write( "41t^2 - 64t - 3536 = 0
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\n" ); document.write( "Solve this equation using the quadratic formula; a=41; b=-64; c=-3536
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\n" ); document.write( "The positive solution: x ~ 10.1 hrs after the 1st car departs \n" ); document.write( "
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