document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=86798>Question 86798</A>This question is from textbook <A HREF=http://www.amazon.com/exec/obidos/ASIN/0321233867/algebrahomeworkh></A><BR>\n" );
document.write( ": <I><SPAN STYLE=\"word-break: break-all;\"> A train goes a distance of 120 miles at a certain speed. If the train had gone 10mph faster it would have arrived 2 hours earlier. How fast is the train going? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #62796 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=62796\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> A train goes a distance of 120 miles at a certain speed. If the train had gone 10mph faster it would have arrived 2 hours earlier. How fast is the train going?<BR>\n" );
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document.write( "Let s = actual speed of the train<BR>\n" );
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document.write( "Write a time equation: Time = Distance/speed<BR>\n" );
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document.write( "Actual time  = Faster speed time + 2 hrs<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=120%2Fs%29 ALIGN=MIDDLE  ALT=\"120%2Fs%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=120%2F%28%28s%2B10%29%29 ALIGN=MIDDLE  ALT=\"120%2F%28%28s%2B10%29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > + 2<BR>\n" );
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document.write( "multiply equation by s(s+10)<BR>\n" );
document.write( "120(s+10) = 120s + 2(s(s+10))<BR>\n" );
document.write( "120s + 1200 = 120s + 2s^2 + 20s<BR>\n" );
document.write( "120s + 1200 = 2s^2 + 140s<BR>\n" );
document.write( "0 = 2s^2 + 140s - 120s - 1200<BR>\n" );
document.write( "2s^2 + 20s - 1200 = 0; a quadratic equation<BR>\n" );
document.write( "Simplify divide by 2:<BR>\n" );
document.write( "s^2 + 10s - 600 = 0<BR>\n" );
document.write( "Factors to:<BR>\n" );
document.write( "(s+30)(s-20) = 0<BR>\n" );
document.write( "s = 20 mph<BR>\n" );
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document.write( "Check solution Using time:<BR>\n" );
document.write( "120/20 = 6 hrs<BR>\n" );
document.write( "120/30 = 4 hrs; 2hrs less  <BR>\n" );
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