document.write( "Question 373944: a boat traveled 9 miles downstream and returned. The total trip took 2.25 hours. If the speed of the current was 3mph, find the speed of the boat in still water. \n" ); document.write( "
Algebra.Com's Answer #266134 by mananth(16946)\"\" \"About 
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a boat traveled 9 miles downstream and returned. The total trip took 2.25 hours. If the speed of the current was 3mph, find the speed of the boat in still water.
\n" ); document.write( "speed of boat in still water = xmph
\n" ); document.write( "speed of current = 3 mph
\n" ); document.write( "..
\n" ); document.write( "upstream speed = x-3
\n" ); document.write( "downstream speed = x+3
\n" ); document.write( "...
\n" ); document.write( "distance traveled = 9 miles
\n" ); document.write( "..
\n" ); document.write( "time upstream + time downstream = total time
\n" ); document.write( "t=d/r
\n" ); document.write( "9/(x+3) +9/(x-3)=2.25
\n" ); document.write( "LCD = (x+3)(x-3)
\n" ); document.write( "9(x-3)+9(x+3)/(x^2-9)=9/4......(2 1/4 = 9/4)
\n" ); document.write( "9x-27+9x+27=9(x^2-9)/4
\n" ); document.write( "18x=(9x^2-81)/4
\n" ); document.write( "72x=9x^2-81
\n" ); document.write( "9x^2-72x-81=0
\n" ); document.write( "/9
\n" ); document.write( "x^2-8x-9=0
\n" ); document.write( "x^2-9x+x-9=0
\n" ); document.write( "x(x-9)+1(x-9)=0
\n" ); document.write( "(x-9)(x+1)=0
\n" ); document.write( "x=9 ignore x=-1
\n" ); document.write( "speed of boat = 9 mph
\n" ); document.write( "...
\n" ); document.write( "m.ananth@hotmail.ca\r
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