document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=759611>Question 759611</A>: <I><SPAN STYLE=\"word-break: break-all;\"> : An airplane flies 594 miles with a 30-mph tailwind and then flies back into the 30-mph wind. If the time for the round trip was four hours, find the speed of the airplane in calm air.\r<BR>\n" );
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document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #462111 by </B><A HREF=/tutors/aboutme.mpl?userid=lwsshak3><B>lwsshak3(11628)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=lwsshak3><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/images/nopicture.jpg><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=462111\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> An airplane flies 594 miles with a 30-mph tailwind and then flies back into the 30-mph wind. If the time for the round trip was four hours, find the speed of the airplane in calm air.<BR>\n" );
document.write( "let x=speed of airplane in calm air<BR>\n" );
document.write( "x+30= speed of airplane with tail wind<BR>\n" );
document.write( "x-30= speed of airplane with downwind<BR>\n" );
document.write( "travel time=distance/speed<BR>\n" );
document.write( "..<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=594%2F%28x-30%29%2B594%2Fx=4 ALIGN=MIDDLE  ALT=\"594%2F%28x-30%29%2B594%2Fx=4\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "LCD:x(x-30)<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=594x%2B594%28x-30%29=4x%28x-30%29 ALIGN=MIDDLE  ALT=\"594x%2B594%28x-30%29=4x%28x-30%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=594x%2B594x-17820=4x%5E2-120x%29 ALIGN=MIDDLE  ALT=\"594x%2B594x-17820=4x%5E2-120x%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "4x^2-1308x+17820=0<BR>\n" );
document.write( "x^2-327x+4455=0<BR>\n" );
document.write( "solve for x by 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( "a=1, b=-327, c=4455<BR>\n" );
document.write( "x&#8776;14.24 (reject)<BR>\n" );
document.write( "or<BR>\n" );
document.write( "x&#8776;312.76<BR>\n" );
document.write( "speed of airplane in calm air&#8776;312.76 mph\r<BR>\n" );
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