document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=989697>Question 989697</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Traveling at full speed on a river, it takes 2 hours for a motorboat to travel 8 miles downstream and 4 miles back upstream. If the current's speed is 2mph, what is the maximum speed of the boat in still water? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #609929 by </B><A HREF=/tutors/aboutme.mpl?userid=josmiceli><B>josmiceli(19441)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=josmiceli><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=josmiceli><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=609929\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Let <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+s+ ALIGN=MIDDLE  ALT=\"+s+\"   DISABLED_style= \"max-width:90%; height:auto;\" > = boat's maximum speed in still water in mi/hr<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+s+%2B+2+ ALIGN=MIDDLE  ALT=\"+s+%2B+2+\"   DISABLED_style= \"max-width:90%; height:auto;\" > = boat's maximum speed going downstream in mi/hr<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+s+-+2+ ALIGN=MIDDLE  ALT=\"+s+-+2+\"   DISABLED_style= \"max-width:90%; height:auto;\" > = boat's maximum speed going upstream in mi/hr<BR>\n" );
document.write( "Let <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+t+ ALIGN=MIDDLE  ALT=\"+t+\"   DISABLED_style= \"max-width:90%; height:auto;\" > = boat's time in hrs to go 8 mi downstream<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+2+-+t+ ALIGN=MIDDLE  ALT=\"+2+-+t+\"   DISABLED_style= \"max-width:90%; height:auto;\" > = boat's time in hrs to go 4 mi upstream<BR>\n" );
document.write( "---------------------<BR>\n" );
document.write( "Going downstream:<BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+8+=+%28+s+%2B+2+%29%2At+ ALIGN=MIDDLE  ALT=\"+8+=+%28+s+%2B+2+%29%2At+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Going upstream:<BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+4+=+%28+s+-+2+%29%2A%28+2+-+t+%29+ ALIGN=MIDDLE  ALT=\"+4+=+%28+s+-+2+%29%2A%28+2+-+t+%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "--------------------------<BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+t+=+8%2F%28+s%2B2+%29+ ALIGN=MIDDLE  ALT=\"+t+=+8%2F%28+s%2B2+%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "and<BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+4+=+%28+s+-+2+%29%2A%28+2+-+t+%29+ ALIGN=MIDDLE  ALT=\"+4+=+%28+s+-+2+%29%2A%28+2+-+t+%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+4%2F%28+s-2+%29+=+2+-+t+ ALIGN=MIDDLE  ALT=\"+4%2F%28+s-2+%29+=+2+-+t+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+4%2F%28+s-2+%29+=+2+-+8%2F%28+s%2B2+%29+ ALIGN=MIDDLE  ALT=\"+4%2F%28+s-2+%29+=+2+-+8%2F%28+s%2B2+%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Multiply both sides by <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+%28+s-2+%29%2A%28+s%2B2+%29+ ALIGN=MIDDLE  ALT=\"+%28+s-2+%29%2A%28+s%2B2+%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+4%2A%28+s%2B2+%29+=+2%2A%28+s%2B2+%29%2A%28+s-2+%29+-+8%2A%28+s-2+%29+ ALIGN=MIDDLE  ALT=\"+4%2A%28+s%2B2+%29+=+2%2A%28+s%2B2+%29%2A%28+s-2+%29+-+8%2A%28+s-2+%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+4s+%2B+8+=+2%2A%28+s%5E2+-+4+%29+-+8s+%2B+16+ ALIGN=MIDDLE  ALT=\"+4s+%2B+8+=+2%2A%28+s%5E2+-+4+%29+-+8s+%2B+16+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+4s+%2B+8+=+2s%5E2+-+8+-+8s+%2B+16+ ALIGN=MIDDLE  ALT=\"+4s+%2B+8+=+2s%5E2+-+8+-+8s+%2B+16+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+2s%5E2+-+12s+=+0+ ALIGN=MIDDLE  ALT=\"+2s%5E2+-+12s+=+0+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+s%2A%28+2s+-+12+%29+=+0+ ALIGN=MIDDLE  ALT=\"+s%2A%28+2s+-+12+%29+=+0+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "The solutions are:<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+s+=+0+ ALIGN=MIDDLE  ALT=\"+s+=+0+\"   DISABLED_style= \"max-width:90%; height:auto;\" > ( the boat is drifting with the current )<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+s+=+6+ ALIGN=MIDDLE  ALT=\"+s+=+6+\"   DISABLED_style= \"max-width:90%; height:auto;\" > <BR>\n" );
document.write( "----------------<BR>\n" );
document.write( "the boat's maximum speed in still water is 6 mi/hr<BR>\n" );
document.write( "----------------<BR>\n" );
document.write( "check:<BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+8+=+%28+s+%2B+2+%29%2At+ ALIGN=MIDDLE  ALT=\"+8+=+%28+s+%2B+2+%29%2At+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+8+=+%28+6+%2B+2+%29%2At+ ALIGN=MIDDLE  ALT=\"+8+=+%28+6+%2B+2+%29%2At+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+8+=+8t+ ALIGN=MIDDLE  ALT=\"+8+=+8t+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+t+=+1+ ALIGN=MIDDLE  ALT=\"+t+=+1+\"   DISABLED_style= \"max-width:90%; height:auto;\" > hr<BR>\n" );
document.write( "and<BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+4+=+%28+s+-+2+%29%2A%28+2+-+t+%29+ ALIGN=MIDDLE  ALT=\"+4+=+%28+s+-+2+%29%2A%28+2+-+t+%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+4+=+%28+6+-+2+%29%2A%28+2+-+t+%29+ ALIGN=MIDDLE  ALT=\"+4+=+%28+6+-+2+%29%2A%28+2+-+t+%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+4+=+4%2A%28+2+-+t+%29+ ALIGN=MIDDLE  ALT=\"+4+=+4%2A%28+2+-+t+%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+4+=+8+-+4t+ ALIGN=MIDDLE  ALT=\"+4+=+8+-+4t+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+4t+=+8+-+4+ ALIGN=MIDDLE  ALT=\"+4t+=+8+-+4+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+4t+=+4+ ALIGN=MIDDLE  ALT=\"+4t+=+4+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+t+=+1+ ALIGN=MIDDLE  ALT=\"+t+=+1+\"   DISABLED_style= \"max-width:90%; height:auto;\" > hr<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+t+%2B+%28+2-t+%29+=+2+ ALIGN=MIDDLE  ALT=\"+t+%2B+%28+2-t+%29+=+2+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+1+%2B+1+=+2+ ALIGN=MIDDLE  ALT=\"+1+%2B+1+=+2+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "OK\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );