document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1023481>Question 1023481</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Two trains start heading toward each other from two cities, the distance between which is 720 km, and meet right in the middle. The second train left 1 hour after the first train, but traveled at a speed 4 km/hour faster than the first train. Find the speed of both trains.<BR>\n" );
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document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #639018 by </B><A HREF=/tutors/aboutme.mpl?userid=ankor@dixie-net.com><B>ankor@dixie-net.com(22740)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=ankor@dixie-net.com><IMG SRC=http://www.algebra.com/images/aboutme-small.gif BORDER=0 alt=\"About Me\" VALIGN=MIDDLE></A>&nbsp;<IMG SRC=http://www.algebra.com/cgi-bin/show-face.mpl?user=ankor@dixie-net.com><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=639018\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Two trains start heading toward each other from two cities, the distance between which is 720 km, and meet right in the middle.<BR>\n" );
document.write( " The second train left 1 hour after the first train, but traveled at a speed 4 km/hour faster than the first train.<BR>\n" );
document.write( " Find the speed of both trains.<BR>\n" );
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document.write( "If they met half-way, each train traveled 360 mi<BR>\n" );
document.write( "let s = speed of the slower train<BR>\n" );
document.write( "then<BR>\n" );
document.write( "(s+4) = speed of the faster train<BR>\n" );
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document.write( "Write a time equation<BR>\n" );
document.write( "Slow train time - fast train time = 1 hr<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=360%2Fs ALIGN=MIDDLE  ALT=\"360%2Fs\"   DISABLED_style= \"max-width:90%; height:auto;\" > - <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=360%2F%28%28s%2B4%29%29 ALIGN=MIDDLE  ALT=\"360%2F%28%28s%2B4%29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > = 1<BR>\n" );
document.write( "multiply equation by s(s+4), cancel the denominators<BR>\n" );
document.write( "360(s+4) - 360s = s(s+4)<BR>\n" );
document.write( "360s + 1440 - 360s = s^2 + 4s<BR>\n" );
document.write( "A quadratic equation<BR>\n" );
document.write( "0 = s^2 + 4s - 1440<BR>\n" );
document.write( "Use the quadratic formula; a=1; b=4; c=-1440. but this will factor to:<BR>\n" );
document.write( "(s-36)(s+40) = 0<BR>\n" );
document.write( "positive solution<BR>\n" );
document.write( "s = 36 mph, speed of the slow train<BR>\n" );
document.write( "then obviously;<BR>\n" );
document.write( "40 mph, the speed of the faster<BR>\n" );
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document.write( "Check this by finding the actual time of each<BR>\n" );
document.write( "360/36 = 10 hrs<BR>\n" );
document.write( "360/40 = 9 hrs, 1 hr less </SPAN>\n" );
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