document.write( "Question 541135: a jet plane traveling at a constant goes 1200 mi with the wind , then turns around and travels for 1000 mi against the wind . if the speed of the wind is a constant 50 mph , and the total flight took 4 hours , find the speed of the plane. \n" ); document.write( "
Algebra.Com's Answer #354070 by mananth(16946)\"\" \"About 
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plane speed x mph
\n" ); document.write( "wind speed 50 mph
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\n" ); document.write( "Distance with wind 1200 miles
\n" ); document.write( "Distance against wind 1000 miles
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\n" ); document.write( "speed with wind x + 50 mph
\n" ); document.write( "speed against x -50 mph
\n" ); document.write( "Total time = 4 hours
\n" ); document.write( "Time with current= 1200 /( x + 50 )
\n" ); document.write( "time against current 1000 / ( x -50 )
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\n" ); document.write( "Time with current + time against = 4 hours
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\n" ); document.write( "1200/( x+50)+1000/(x-50)=4
\n" ); document.write( "LCD =(x+50)*(x-50)
\n" ); document.write( "multiply the equation by the LCD
\n" ); document.write( "we get
\n" ); document.write( "1200*(x -50)+1000(x+50)=4
\n" ); document.write( "1200x-60000+1000x+50000 =4x^2
\n" ); document.write( "2200x-10000=4x^2-10000
\n" ); document.write( "4x^2-2200x+10000-10000 = 0
\n" ); document.write( "4x^2-2200x= 0
\n" ); document.write( "/ 4
\n" ); document.write( "X^2-550 x=0
\n" ); document.write( "x^2=550x
\n" ); document.write( "x=550 mph\r
\n" ); document.write( "\n" ); document.write( "m.ananth@hotmail.ca
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