document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=415647>Question 415647</A>: <I><SPAN STYLE=\"word-break: break-all;\"> An airplane travels 400km at a certain speed. One year later, the same airplane does the same trip at a speed 50km/hr faster than a year ago, and it takes one hour less time. What was the speed of the airplane one year ago </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #291349 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=291349\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> speed	x					<BR>\n" );
document.write( "speed	x+50 after one year			<BR>\n" );
document.write( "						<BR>\n" );
document.write( "Distance = same	400km			<BR>\n" );
document.write( "original time – time with increased speed =1hour<BR>\n" );
document.write( "t=d/t						<BR>\n" );
document.write( "400/x-400/(x+400	)=1				<BR>\n" );
document.write( "LCD= (x+	400)	<BR>\n" );
document.write( "multiply by LCD																<BR>\n" );
document.write( "400(x+400)-400x	=x(x+400	)<BR>\n" );
document.write( "400x+160000-400x	=1X^2+400x				<BR>\n" );
document.write( "160000=X^2+400x							<BR>\n" );
document.write( "X^2+400x-160000	=0<BR>\n" );
document.write( "solve using quadratic formula\r<BR>\n" );
document.write( "\n" );
document.write( "a= 1  , b = 400  , c ==-160000     .\r<BR>\n" );
document.write( "\n" );
document.write( "b^2-4ac=800000\r<BR>\n" );
document.write( "\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;\" >\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x1=%28-400%2Bsqrt%28800000%29%29%2F%282%29 ALIGN=MIDDLE  ALT=\"x1=%28-400%2Bsqrt%28800000%29%29%2F%282%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "x1= 247.21 <BR>\n" );
document.write( "x2 is negative so ignore<BR>\n" );
document.write( "original speed = 247.21 mph<BR>\n" );
document.write( "after one year speed= 297.21 mph\r<BR>\n" );
document.write( "\n" );
document.write( "...<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x2=%28-b-sqrt%28b%5E2-4ac%29%29%2F%282a%29 ALIGN=MIDDLE  ALT=\"x2=%28-b-sqrt%28b%5E2-4ac%29%29%2F%282a%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "							<BR>\n" );
document.write( "			<BR>\n" );
document.write( "													<BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );