document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=671673>Question 671673</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A jet flew 1200 miles with a tailwind of 50 mph. The tailwind changed to 20 mph for the remaining 520 miles of the flight. The total time of the flight was 3 hours. Find the speed of the jet relative to the ground. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #417524 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=417524\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> let the speed of jet be x\r<BR>\n" );
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document.write( "first part\r<BR>\n" );
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document.write( "speed = x+50\r<BR>\n" );
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document.write( "second part speed = x+20\r<BR>\n" );
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document.write( "Time first part = 1200/(x+50)<BR>\n" );
document.write( "second part time = 520/(x+20)\r<BR>\n" );
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document.write( "Time first part + time second part = 3\r<BR>\n" );
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document.write( "1200/(x+50) + 520/(x+20)=3\r<BR>\n" );
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document.write( "LCD= (x+50)(x+20)= x^2+70x+1000)\r<BR>\n" );
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document.write( "Multiply equation by the LCD\r<BR>\n" );
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document.write( "1200(x+20) +520(x+50)=3(x^2+70x+1000)\r<BR>\n" );
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document.write( "1200x+24000+520x+26000=3x^2+210x+3000\r<BR>\n" );
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document.write( "1720x+50000=3x^2+210x+3000\r<BR>\n" );
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document.write( "3x^2+210x-1720x+3000-50000=0<BR>\n" );
document.write( "3x^2-1510x-47000=0\r<BR>\n" );
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document.write( "Find the roots of the equation by quadratic formula						<BR>\n" );
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document.write( "a=	3    	b=	-1510	c=	-47000	<BR>\n" );
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document.write( "b^2-4ac=	2280100	-	-564000			<BR>\n" );
document.write( "b^2-4ac=	2844100		<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=sqrt%28%092844100%09%29 ALIGN=MIDDLE  ALT=\"sqrt%28%092844100%09%29\"   DISABLED_style= \"max-width:90%; height:auto;\" >=	1686.45<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=(	1510	+	1686.45	)/	6	<BR>\n" );
document.write( "x1=	532.74					<BR>\n" );
document.write( "x2=(	1510	-	1686.45	)/	6	<BR>\n" );
document.write( "x2=	-29.41					<BR>\n" );
document.write( "Ignore negative value						<BR>\n" );
document.write( "x	=	532.74	mph	the speed of plane\r<BR>\n" );
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document.write( "m.ananth@hotmail.ca		\r<BR>\n" );
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document.write( " </SPAN>\n" );
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