document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=398138>Question 398138</A>: <I><SPAN STYLE=\"word-break: break-all;\"> word problem associated with quadratic equation chapter::\r<BR>\n" );
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document.write( "a motorboat maintained a constant speed of 12 mph relative to the water going 23 miles upstream then returning.  Total time for the trip was 24 hours.  Using this information provided, what is the speed of the current in mph? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #282133 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=282133\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> a motorboat maintained a constant speed of 12 mph relative to the water going<BR>\n" );
document.write( " 23 miles upstream then returning.<BR>\n" );
document.write( " Total time for the trip was 24 hours.<BR>\n" );
document.write( " Using this information provided, what is the speed of the current in mph?<BR>\n" );
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document.write( "Let x = speed of the current<BR>\n" );
document.write( "then<BR>\n" );
document.write( "(12-x) = effective speed upstream<BR>\n" );
document.write( "and<BR>\n" );
document.write( "(12+x) = effective speed downstream<BR>\n" );
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document.write( "Write a time equation; time = dist/speed<BR>\n" );
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document.write( "time upstr + time downstr = 24 hrs<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=23%2F%28%2812-x%29%29 ALIGN=MIDDLE  ALT=\"23%2F%28%2812-x%29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > + <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=23%2F%28%2812%2Bx%29%29 ALIGN=MIDDLE  ALT=\"23%2F%28%2812%2Bx%29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > = 24<BR>\n" );
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document.write( "Multiply equation by (12-x)(12+x) to get rid of the denominators, results:<BR>\n" );
document.write( "23(12+x) + 23(12-x) = 24(12-x)(12+x)<BR>\n" );
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document.write( "276 + 23x + 276 - 23x = 24(144 - x^2)<BR>\n" );
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document.write( "552 = 3456 - 24x^2<BR>\n" );
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document.write( "24x^2 = 3456 - 552<BR>\n" );
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document.write( "24x^2 = 2904<BR>\n" );
document.write( "divide both sides by 24<BR>\n" );
document.write( "x^2 = 121<BR>\n" );
document.write( "x = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=sqrt%28121%29 ALIGN=MIDDLE  ALT=\"sqrt%28121%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "x = 11 mph is the speed of the current<BR>\n" );
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document.write( "That seems high, but let's check the time each way<BR>\n" );
document.write( "23/(12+11) = 1.0 hr<BR>\n" );
document.write( "23/(12-11) = 23 hrs<BR>\n" );
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document.write( "round trip time: 24 hrs, which confirms our solution of x = 11 mph current </SPAN>\n" );
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