document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=121894>Question 121894</A>This question is from textbook <A HREF=http://www.amazon.com/exec/obidos/ASIN/0395535921/algebrahomeworkh></A><BR>\n" );
document.write( ": <I><SPAN STYLE=\"word-break: break-all;\"> In a 16 km cross-country race Brett skied the first 7 km at a constant speed and then increased by 3 km/h for the last 9 km. If he finished the entire race in 1 h 20 min, what was his speed for the first 7 km?\r<BR>\n" );
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document.write( "I have:\r<BR>\n" );
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document.write( "d=rt<BR>\n" );
document.write( "7=(x+3)t<BR>\n" );
document.write( "yeah...idk.thats wrong though\r<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 #89578 by </B><A HREF=/tutors/aboutme.mpl?userid=scott8148><B>scott8148(6628)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=scott8148><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=scott8148><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=89578\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> try t=d/r __ let x=\"speed for first 7 km\"\r<BR>\n" );
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document.write( "for first 7 km __ t=7/x\r<BR>\n" );
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document.write( "for last 9 km __ t=9/(x+3)\r<BR>\n" );
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document.write( "total time is 4/3, so 4/3=(7/x)+(9/(x+3))\r<BR>\n" );
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document.write( "multiplying by 3x(x+3) gives 4x^2+12x=21x+63+27x __ 4x^2-36x-63=0\r<BR>\n" );
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document.write( "factoring gives (2x-21)(2x+3)=0 </SPAN>\n" );
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