document.write( "Question 392018: It takes a crew 1 hour and 30 minutes longer to go 12 miles upstream than to return. Find their rate in still water if the rate of the current is 2mph. \n" ); document.write( "
Algebra.Com's Answer #278312 by mananth(16946)\"\" \"About 
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It takes a crew 1 hour and 30 minutes longer to go 12 miles upstream than to return. Find their rate in still water if the rate of the current is 2mph.
\n" ); document.write( "..
\n" ); document.write( "let speed of boat be x mph
\n" ); document.write( "current speed = 2 mph.
\n" ); document.write( "upstream speed = x-2 mph
\n" ); document.write( "downstream speed = x-2 mph
\n" ); document.write( "..
\n" ); document.write( "time = distance / speed
\n" ); document.write( "upstream time -downstream time = 1 1/2 = 3/2 hours
\n" ); document.write( "\"x%2F%28x-2%29+-+x%2F%28x%2B2%29+=+3%2F2\"
\n" ); document.write( "LCD = (x+2)(x-2)
\n" ); document.write( "multiply by (x+2)(x-2)
\n" ); document.write( "..
\n" ); document.write( "x(x+2)-x(x-2)/(x+2)(x-2) = 3/2
\n" ); document.write( "x^2+2x-x^2+2x/(x+2)(x-2)=3/2
\n" ); document.write( "4x/(x+2)(x-2)= 3/2
\n" ); document.write( "cross multiply
\n" ); document.write( "8x= 3(x+2)(x-2)
\n" ); document.write( "8x=3x^2-12
\n" ); document.write( "3x^2-8x-12=0
\n" ); document.write( "Find roots by quadratic equation
\n" ); document.write( "b^2-4ac=208
\n" ); document.write( "\"x1=+%288%2Bsqrt%28208%29%29%2F3\"
\n" ); document.write( "x1= 3.73 mph speed of boat.
\n" ); document.write( "x2 is negative so ignore
\n" ); document.write( "...
\n" ); document.write( "m.ananth@hotmail.ca \n" ); document.write( "
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