document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=122105>Question 122105</A>This question is from textbook <A HREF=http://www.amazon.com/exec/obidos/ASIN/0395352495/algebrahomeworkh>algebra: structure and Method: book 1</A><BR>\n" );
document.write( ": <I><SPAN STYLE=\"word-break: break-all;\"> I I increase my usual driving speed by 10 km/h, I can drive the 255 km trip to Nashville in 24 min less than usual. How fast do I usually drive? PLEASE HELP!!!! There is not an answer in the back, and I also don't know what to do!!!!HELP!!!!!!!!!!!!!!!!!!! I am sorry if this is not enough info, but that is all there is in the book. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #89691 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=89691\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> If I increase my usual driving speed by 10 km/h, I can drive the 255 km trip to Nashville in 24 min less than usual. How fast do I usually drive?<BR>\n" );
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document.write( "Let x = the usual driving speed<BR>\n" );
document.write( "then<BR>\n" );
document.write( "(x+10) = the increased driving speed<BR>\n" );
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document.write( "Convert 24 min to hrs: <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=24%2F60 ALIGN=MIDDLE  ALT=\"24%2F60\"   DISABLED_style= \"max-width:90%; height:auto;\" > = .4 hrs<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=distance%2Fspeed ALIGN=MIDDLE  ALT=\"distance%2Fspeed\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
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document.write( "Usual time = faster time + .4 hrs<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=255%2Fx ALIGN=MIDDLE  ALT=\"255%2Fx\"   DISABLED_style= \"max-width:90%; height:auto;\" > = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=255%2F%28%28x%2B10%29%29 ALIGN=MIDDLE  ALT=\"255%2F%28%28x%2B10%29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > + .4<BR>\n" );
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document.write( "Multiply the equation by x(x+10) to get rid of the denominators; results:<BR>\n" );
document.write( "255(x+10) = 255x + .4(x(x+10)<BR>\n" );
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document.write( "255x + 2550 = 255x = .4x^2 + 4x<BR>\n" );
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document.write( "0 = 255x - 255x + .4x^2 + 4x - 2550<BR>\n" );
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document.write( ".4x^2 + 4x - 2550 = 0<BR>\n" );
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document.write( "Get rid of the decimal and make the coefficient of x^2 = 1<BR>\n" );
document.write( "Multiply equation by 2.5 and you have:<BR>\n" );
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document.write( "1x^2 + 10x - 6375 = 0<BR>\n" );
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document.write( "This will factor to:<BR>\n" );
document.write( "(x + 85)(x - 75) = 0<BR>\n" );
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document.write( "Positive solution only needed here:<BR>\n" );
document.write( "x = 75 km/h is his usual speed<BR>\n" );
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document.write( "Check our solution by finding the time difference between the two scenarios<BR>\n" );
document.write( "255/75 = 3.4 hrs<BR>\n" );
document.write( "255/85 = 3.0 hrs<BR>\n" );
document.write( "----------------<BR>\n" );
document.write( "difference .4 hrs   </SPAN>\n" );
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