document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=388274>Question 388274</A>: <I><SPAN STYLE=\"word-break: break-all;\"> 3.mr. kumar lives in the eastern part of the singapore. he visits his aged parents who lives 36 km away, evry weekends. he finds that if he increases the average speed of his vehicle by 12 km/h.he could save 9 min of his travelling time. find the speed at which he travels before the increase in speed </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #274602 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=274602\">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=t ALIGN=MIDDLE  ALT=\"t\"   DISABLED_style= \"max-width:90%; height:auto;\" > = his time before he increases his speed.<BR>\n" );
document.write( "Let <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=r ALIGN=MIDDLE  ALT=\"r\"   DISABLED_style= \"max-width:90%; height:auto;\" > = his rate before he increases his speed<BR>\n" );
document.write( "given:<BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=36+=+r%2At ALIGN=MIDDLE  ALT=\"36+=+r%2At\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=36+=+%28r+%2B+12%29%2A%28t+-+9%2F60%29 ALIGN=MIDDLE  ALT=\"36+=+%28r+%2B+12%29%2A%28t+-+9%2F60%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "----------------------<BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=36+=+r%2At+%2B+12t+-+%283%2F20%29%2Ar+-+9%2F5 ALIGN=MIDDLE  ALT=\"36+=+r%2At+%2B+12t+-+%283%2F20%29%2Ar+-+9%2F5\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Substituting from (1):<BR>\n" );
document.write( " <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=36+=+36+%2B+12%2A%2836%2Fr%29+-+%283%2F20%29%2Ar+-+9%2F5 ALIGN=MIDDLE  ALT=\"36+=+36+%2B+12%2A%2836%2Fr%29+-+%283%2F20%29%2Ar+-+9%2F5\"   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=20r ALIGN=MIDDLE  ALT=\"20r\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=0+=+24%2A360+-+3r%5E2+-+36r ALIGN=MIDDLE  ALT=\"0+=+24%2A360+-+3r%5E2+-+36r\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=3r%5E2+%2B+36r+-+8640+=+0+ ALIGN=MIDDLE  ALT=\"3r%5E2+%2B+36r+-+8640+=+0+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=r%5E2+%2B+12r+-+2880+=+0 ALIGN=MIDDLE  ALT=\"r%5E2+%2B+12r+-+2880+=+0\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Use 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( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=a+=+1 ALIGN=MIDDLE  ALT=\"a+=+1\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=b+=+12 ALIGN=MIDDLE  ALT=\"b+=+12\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=c+=+-2880 ALIGN=MIDDLE  ALT=\"c+=+-2880\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x+=+%28-12+%2B-+sqrt%28+12%5E2-4%2A1%2A%28-2880%29+%29%29%2F%282%2Aa%29+ ALIGN=MIDDLE  ALT=\"x+=+%28-12+%2B-+sqrt%28+12%5E2-4%2A1%2A%28-2880%29+%29%29%2F%282%2Aa%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" > <BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x+=+%28-12+%2B-+sqrt%28+144+%2B+11520+%29%29%2F2+ ALIGN=MIDDLE  ALT=\"x+=+%28-12+%2B-+sqrt%28+144+%2B+11520+%29%29%2F2+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x+=+%28-12+%2B-+sqrt%28+11664+%29%29%2F2+ ALIGN=MIDDLE  ALT=\"x+=+%28-12+%2B-+sqrt%28+11664+%29%29%2F2+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=r+=+%28-12+%2B+108%29%2F2 ALIGN=MIDDLE  ALT=\"r+=+%28-12+%2B+108%29%2F2\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=r+=+96%2F2 ALIGN=MIDDLE  ALT=\"r+=+96%2F2\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=r+=+48 ALIGN=MIDDLE  ALT=\"r+=+48\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "the other root is ignored since it is negative<BR>\n" );
document.write( "His speed before the increase is 48 km/hr<BR>\n" );
document.write( "Check answer:<BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=36+=+r%2At ALIGN=MIDDLE  ALT=\"36+=+r%2At\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=t+=+36%2F48 ALIGN=MIDDLE  ALT=\"t+=+36%2F48\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=t+=+3%2F4 ALIGN=MIDDLE  ALT=\"t+=+3%2F4\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=36+=+%28r+%2B+12%29%2A%28t+-+9%2F60%29 ALIGN=MIDDLE  ALT=\"36+=+%28r+%2B+12%29%2A%28t+-+9%2F60%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=36+=+%2848+%2B+12%29%2A%283%2F4+-+9%2F60%29 ALIGN=MIDDLE  ALT=\"36+=+%2848+%2B+12%29%2A%283%2F4+-+9%2F60%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=36+=+60%2A%283%2A15+-+9%29%2F60 ALIGN=MIDDLE  ALT=\"36+=+60%2A%283%2A15+-+9%29%2F60\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=36+=+45+-+9 ALIGN=MIDDLE  ALT=\"36+=+45+-+9\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=36+=+36 ALIGN=MIDDLE  ALT=\"36+=+36\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "OK </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );