document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=428032>Question 428032</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A pilot flies 500 miles against a<BR>\n" );
document.write( "20-mile-per-hour wind. On the next day, the pilot<BR>\n" );
document.write( "flies back home with a 10-mile-per-hour tail wind.<BR>\n" );
document.write( "The total trip (both ways) takes 4 hours. Find the<BR>\n" );
document.write( "speed of the airplane without a wind. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #297574 by </B><A HREF=/tutors/aboutme.mpl?userid=mananth><B>mananth(16946)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=mananth><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=mananth><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=297574\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> plane speed in still air		x   		<BR>\n" );
document.write( "wind speed		20		<BR>\n" );
document.write( "				<BR>\n" );
document.write( "against wind x-	10		<BR>\n" );
document.write( "with wind x+10		<BR>\n" );
document.write( "				<BR>\n" );
document.write( "Distance= 500	miles		<BR>\n" );
document.write( "				<BR>\n" );
document.write( "Time agianst + time with wind =4	hours<BR>\n" );
document.write( "t=d/r				<BR>\n" );
document.write( "500/(x+20)+500/(x-20)=	4<BR>\n" );
document.write( "LCD =	(x-20)(x	+20)				<BR>\n" );
document.write( "500*(x-20)+500(x+20)=4<BR>\n" );
document.write( "500x-10000+500x+10000=4x ^2-400<BR>\n" );
document.write( "1000x=4x ^2-400							<BR>\n" );
document.write( "4x^2-1000x-400=0								<BR>\n" );
document.write( "Find the roots of the equation by quadratic formula	<BR>\n" );
document.write( "a=	4	b=	-1000	c=	-400				<BR>\n" );
document.write( "b^2-4ac=	1000000	-	6400										<BR>\n" );
document.write( "b^2-4ac=	1006400												<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x=%28-b%2B-sqrt%28b%5E2-4ac%29%29%2F%282a%29 ALIGN=MIDDLE  ALT=\"x=%28-b%2B-sqrt%28b%5E2-4ac%29%29%2F%282a%29\"   DISABLED_style= \"max-width:90%; height:auto;\" >													<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x1=%28-b%2Bsqrt%28b%5E2-4ac%29%29%2F%282a%29 ALIGN=MIDDLE  ALT=\"x1=%28-b%2Bsqrt%28b%5E2-4ac%29%29%2F%282a%29\"   DISABLED_style= \"max-width:90%; height:auto;\" >													<BR>\n" );
document.write( "x1=(1000+1003.19	)/8								<BR>\n" );
document.write( "x1=	250.4	mph											<BR>\n" );
document.write( "x2=(1000-1003.19) /8									<BR>\n" );
document.write( "x2=-0.4												<BR>\n" );
document.write( "Ignore negative value													<BR>\n" );
document.write( "250.4	mph	=speed	in still air						<BR>\n" );
document.write( "				<BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );