document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=162021>Question 162021</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Joel drives his car for 20km at a certain speed.At a distance,he increases his speed by 5 km per hour and drives for an additional 20km.If the total trip taken is 1 hour,what is his original speed? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #119415 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=119415\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Joel drives his car for 20km at a certain speed; he increases his speed by 5 km<BR>\n" );
document.write( " per hour and drives for an additional 20km. If the total trip taken.<BR>\n" );
document.write( " is 1 hour, what is his original speed?<BR>\n" );
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document.write( "Let s = his original speed<BR>\n" );
document.write( "then<BR>\n" );
document.write( "(s+5) = his increased speed<BR>\n" );
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document.write( "Write a time equation; Time = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=dist%2Fspeed ALIGN=MIDDLE  ALT=\"dist%2Fspeed\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( ";<BR>\n" );
document.write( "Orig speed time + increase speed time = 1 hour<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=20%2Fs ALIGN=MIDDLE  ALT=\"20%2Fs\"   DISABLED_style= \"max-width:90%; height:auto;\" > + <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=20%2F%28%28s%2B5%29%29 ALIGN=MIDDLE  ALT=\"20%2F%28%28s%2B5%29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > = 1<BR>\n" );
document.write( ";<BR>\n" );
document.write( "Multiply equation by s(s+5), results;<BR>\n" );
document.write( "20(s+5) + 20s = s(s+5)<BR>\n" );
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document.write( "20s + 100 + 20x = s^2 + 5s<BR>\n" );
document.write( "40s + 100 = s^2 + 5s<BR>\n" );
document.write( ":<BR>\n" );
document.write( "0 = s^2 + 5s - 40s - 100<BR>\n" );
document.write( "A quadratic equation:<BR>\n" );
document.write( "s^2 - 35s - 100 = 0<BR>\n" );
document.write( "Solve this with the quadratic formula;<BR>\n" );
document.write( " <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+ ALIGN=MIDDLE  ALT=\"x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "in this problem: a=1, b=-35, c=-100<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=s+=+%28-%28-35%29+%2B-+sqrt%28-35%5E2+-+4%2A1%2A-100+%29%29%2F%282%2A1%29+ ALIGN=MIDDLE  ALT=\"s+=+%28-%28-35%29+%2B-+sqrt%28-35%5E2+-+4%2A1%2A-100+%29%29%2F%282%2A1%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=s+=+%2835+%2B-+sqrt%281225+%2B+400+%29%29%2F%282%29+ ALIGN=MIDDLE  ALT=\"s+=+%2835+%2B-+sqrt%281225+%2B+400+%29%29%2F%282%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Do the math here, the positive solution should be:<BR>\n" );
document.write( "s = 37.656 km/hr is the original speed<BR>\n" );
document.write( ";<BR>\n" );
document.write( ":<BR>\n" );
document.write( "Check solution on a calc:<BR>\n" );
document.write( "20/37.656 + 20/42.656 = .99998 ~ 1\r<BR>\n" );
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