document.write( "Question 831367: A jet plane, flying 160 mph faster than a propeller plane, travels 4800 miles in 5 hours less time than the propeller plane takes to fly the same distance. How fast does each plane fly?
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Algebra.Com's Answer #501273 by josgarithmetic(39620)\"\" \"About 
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This general type of travel problem seems to be becoming common.\r
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\n" ); document.write( "\n" ); document.write( "A jet plane, flying v mph faster than a propeller plane, travels d miles in p hours less time than the propeller plane takes to fly the same distance. How fast does each plane fly? Assume v and p are positive numbers.\r
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\n" ); document.write( "\n" ); document.write( "Additionally, let r be the speed of the propeller plane; and let h be the time for the propeller plane to make the d distance.\r
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\n" ); document.write( "\n" ); document.write( "_______________speed___________time________________distance
\n" ); document.write( "JET____________r+v____________h-p__________________d
\n" ); document.write( "PROP____________r______________h___________________d\r
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\n" ); document.write( "\n" ); document.write( "The UNKNOWN variables are r and h. Use the uniform rates equation for travel, R*T=D, for Rate, Time, Distance.\r
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\n" ); document.write( "\n" ); document.write( "EQUATIONS TO BEGIN:
\n" ); document.write( "\"%28r%2Bv%29%28h-p%29=d\", and \"rh=d\";\r
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\n" ); document.write( "\n" ); document.write( "The steps will very neatly give a useful equation...
\n" ); document.write( "...starting with the jet's equation.
\n" ); document.write( "\"rh%2Bvh-rp-vp=d\"
\n" ); document.write( "Notice that we already have the propeller plane's equation rh=d allowing a substitution:
\n" ); document.write( "\"d%2Bvh-rp-vp=d\"
\n" ); document.write( "\"vh-pr-pv=0\"
\n" ); document.write( "We can again use the propeller's simple equation, as \"h=d%2Fr\", and then get
\n" ); document.write( "\"v%28d%2Fr%29-pr-pv=0\"
\n" ); document.write( "\"vd-pr%5E2-pvr=0\"
\n" ); document.write( "\"-pr%5E2-pvr%2Bvd=0\"
\n" ); document.write( "\"highlight%28pr%5E2%2Bpvr-vd=0%29\"-----QUADRATIC EQUATION IN THE ONE VARIABLE, r. Use general solution to a quadratic equation to solve for r. Use found value to get the value for h.
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