document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=206289>Question 206289</A>: <I><SPAN STYLE=\"word-break: break-all;\"> an airplane flies between two cities 450 kilometers apart traveling with a wind of 45mph going and against the same wind when returning. the trip out takes one less hour than the return trip. what is the speed of the plane in still air? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #156101 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=156101\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> an airplane flies between two cities 450 kilometers apart traveling with a wind<BR>\n" );
document.write( " of 45 mph going and against the same wind when returning. <BR>\n" );
document.write( "the trip out takes one less hour than the return trip. <BR>\n" );
document.write( "what is the speed of the plane in still air?<BR>\n" );
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document.write( "Let s = plane speed in still air<BR>\n" );
document.write( "then<BR>\n" );
document.write( "(s+45) = speed with the wind<BR>\n" );
document.write( "and<BR>\n" );
document.write( "(s-45) = speed against the wind<BR>\n" );
document.write( ";<BR>\n" );
document.write( "Write a time equation: Time = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=dist%2Fspeed ALIGN=MIDDLE  ALT=\"dist%2Fspeed\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
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document.write( "trip out + 1 hour = trip back<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=450%2F%28%28s%2B45%29%29 ALIGN=MIDDLE  ALT=\"450%2F%28%28s%2B45%29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > + 1 = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=450%2F%28%28s-45%29%29 ALIGN=MIDDLE  ALT=\"450%2F%28%28s-45%29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Multiply equation by (s+45)(s-45), results<BR>\n" );
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document.write( "450(s-45) + (s+45)(s-45)*1 = 450(s+45)<BR>\n" );
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document.write( "450s - 20250 + s^2 - 2025 = 450s + 20250<BR>\n" );
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document.write( "Arrange on the left<BR>\n" );
document.write( "s^2 + 450s - 450s - 2025 - 20250 - 20250 = 0 <BR>\n" );
document.write( ":<BR>\n" );
document.write( "s^2 - 42525 = 0<BR>\n" );
document.write( ";<BR>\n" );
document.write( "s^2 = 42525<BR>\n" );
document.write( "s = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=sqrt%2842525%29 ALIGN=MIDDLE  ALT=\"sqrt%2842525%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "s = 206.2 speed in still air<BR>\n" );
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document.write( ":<BR>\n" );
document.write( "Check solution by finding the times of each trip<BR>\n" );
document.write( "450/251.2 = 1.79 hrs<BR>\n" );
document.write( "450/161.2 = 2.79 hrs<BR>\n" );
document.write( "differs by 1 hr </SPAN>\n" );
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