document.write( "Question 548516: The speed of an airplane still in the air is 203 km/hr. The plane travels 666 km against wind and 769 km with the wind in a total time of 11 hours. What is the speed of the wind (km/hr.)? \n" ); document.write( "

Algebra.Com's Answer #357091 by mananth(16946) $\"\"$ $\"About$

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plane speed = 203 km/h
\n" ); document.write( "wind speed = x km/h
\n" ); document.write( "against wind = 203 - x
\n" ); document.write( "with wind = 203 + x
\n" ); document.write( "Total Time= 11.00 hours
\n" ); document.write( "Time against + time with = 11
\n" ); document.write( "666/(203-x)+769 /(203+x )=11
\n" ); document.write( "666(203 +x)+769(203-x)= 11
\n" ); document.write( "135198+666x+156107-769x =11(203^2-x^2)
\n" ); document.write( "135198+666x+156107-769x =453299-11x^2\r
\n" ); document.write( "\n" ); document.write( "11x^2-103x-161994=0\r
\n" ); document.write( "\n" ); document.write( "Find the roots of the equation by quadratic formula
\n" ); document.write( "
\n" ); document.write( "a=11 ,b=-103 ,c=-161994
\n" ); document.write( "
\n" ); document.write( "b^2-4ac= 10609 + 7127736
\n" ); document.write( "b^2-4ac= 7138345
\n" ); document.write( " $\"%09sqrt%28%097138345%09%29=%092671.77%09\"$
\n" ); document.write( " $\"x=%28-b%2B-sqrt%28b%5E2-4ac%29%29%2F%282a%29\"$
\n" ); document.write( " $\"x1=%28-b%2Bsqrt%28b%5E2-4ac%29%29%2F%282a%29\"$
\n" ); document.write( "x1=( 103 + 2671.77 )/ 22
\n" ); document.write( "x1= 126.13
\n" ); document.write( "x2=( 103 -2671.77 ) / 22
\n" ); document.write( "x2= -116.76
\n" ); document.write( "Ignore negative value
\n" ); document.write( "wind speed 126.13 mph
\n" ); document.write( "
\n" ); document.write( " \r
\n" ); document.write( "\n" ); document.write( " \n" ); document.write( "

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