document.write( "Question 497459: a boat travel 10 kilometer. upstream and 10 kilometer. back. the trip upstream and back takes 1.5 hours. If the speed of the current is 5 kilometer. per hour what is the speed of the boat in still water \n" ); document.write( "
Algebra.Com's Answer #336736 by mananth(16946)\"\" \"About 
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Boat speed x
\n" ); document.write( "current speed 5
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\n" ); document.write( "against current x- 5 kph
\n" ); document.write( "with current x+ 5 kph
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\n" ); document.write( "Distance= 10 km
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\n" ); document.write( "Time against + time with = 1.5 hours\r
\n" ); document.write( "\n" ); document.write( "10 /( x + 5 ) + 10 /(x - 5 ) = 1.5
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\n" ); document.write( "LCD = (x - 5 ) ( x + 5 )
\n" ); document.write( "10 *( x - 5 ) + 10 (x + 5 ) = 1.5
\n" ); document.write( "10 x - 50 + 10 x + 50 = 1.5 ( x ^2 - 25 )
\n" ); document.write( "20 x = 1.5 x ^2 - 37.5
\n" ); document.write( "1.5 x ^2 - -20 x - 37.5
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\n" ); document.write( "Find the roots of the equation by quadratic formula
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\n" ); document.write( "a= 1.5 , b= -20 , c= -37.5
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\n" ); document.write( "b^2-4ac= 400 + 225
\n" ); document.write( "b^2-4ac= 625 \"%09sqrt%28%09625%09%29=%0925%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=( 20 + 25 )/ 3
\n" ); document.write( "x1= 15
\n" ); document.write( "x2=( 20 -25 ) / 3
\n" ); document.write( "x2= -1.67
\n" ); document.write( "Ignore negative value
\n" ); document.write( "15 mph=speed of boat\r
\n" ); document.write( "\n" ); document.write( "m.ananth@hotmail.ca
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