document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=117642>Question 117642</A>: <I><SPAN STYLE=\"word-break: break-all;\"> THE SPEED OF AN AIRPLANE IN STILL AIR IS 224KM/H. THE PLANE TRAVELS 733KM AGAINST THE WIND AND 1075KM WITH THE WIND IN A TOTAL TIME OF 15HR. WHAT IS THE SPEED OF THE WIND </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #85810 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=85810\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> THE SPEED OF AN AIRPLANE IN STILL AIR IS 224KM/H. THE PLANE TRAVELS 733KM AGAINST THE WIND AND 1075KM WITH THE WIND IN A TOTAL TIME OF 15 HR. WHAT IS THE SPEED OF THE WIND<BR>\n" );
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document.write( "Let x = wind speed<BR>\n" );
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document.write( "(224-x) = speed against the wind<BR>\n" );
document.write( "and<BR>\n" );
document.write( "(224+x) = speed with the wind<BR>\n" );
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document.write( "The total time is given as 15 hrs, write a time equation: Time = Dist/speed<BR>\n" );
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document.write( "Time with + time against = 15 hrs<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=1075%2F%28%28224%2Bx%29%29 ALIGN=MIDDLE  ALT=\"1075%2F%28%28224%2Bx%29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > + <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=733%2F%28%28224-x%29%29 ALIGN=MIDDLE  ALT=\"733%2F%28%28224-x%29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > = 15<BR>\n" );
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document.write( "Multiply equation by (224+x)(224-x) to get rid of the denominators, results<BR>\n" );
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document.write( "1075(224-x) + 733(224+x) = 15(224+x)(224-x)<BR>\n" );
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document.write( "240800 - 1075x + 164192 + 733x = 15(50176 - x^2)<BR>\n" );
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document.write( "-1075x + 733x + 240800 + 164192 = 752640 - 15x^2<BR>\n" );
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document.write( "+15x^2 - 342x + 404992 - 752640 = 0; arrange as a quadratic equation<BR>\n" );
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document.write( "15x^2 - 342x - 347648 = 0<BR>\n" );
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document.write( "Solve this using the quadratic formula; a=15, b=-342, c=-347648<BR>\n" );
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document.write( "I got a positive solution (approximately): x = 164.06 is the speed of the wind<BR>\n" );
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document.write( "Checking our solution:<BR>\n" );
document.write( "224 - 164.06 = 59.94 km/hr against the wind<BR>\n" );
document.write( "and<BR>\n" );
document.write( "224 + 164.06 = 388.06 km/hr with the wind<BR>\n" );
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document.write( "1075/388.06 + 733/59.94 = <BR>\n" );
document.write( "2.77 + 12.23 = 15 hrs </SPAN>\n" );
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