document.write( "Question 548493: a boat completes a trip from riverton to clear creek and back each weekday.the distance one way is 60 miles ,and the speed of the current in the river is 4 miles per hour .if the round trip takes 8 hours ,determine the speed of the boat in still water \n" ); document.write( "
Algebra.Com's Answer #359220 by lwsshak3(11628)\"\" \"About 
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a boat completes a trip from riverton to clear creek and back each weekday.the distance one way is 60 miles ,and the speed of the current in the river is 4 miles per hour .if the round trip takes 8 hours ,determine the speed of the boat in still water
\n" ); document.write( "**
\n" ); document.write( "let x=speed of boat in still water
\n" ); document.write( "x+4=speed of boat with current
\n" ); document.write( "x-4=speed of boat against current
\n" ); document.write( "Travel time=distance/speed
\n" ); document.write( "..
\n" ); document.write( "60/(x+4)+60/(x-4)=8
\n" ); document.write( "LCD: (x+4)(x-4)
\n" ); document.write( "60(x-4)+60(x+4)=8(x+4)(x-4)=8(x^2-16)
\n" ); document.write( "60x-240+60x+240=8x^2-128
\n" ); document.write( "120x=8x^2-128
\n" ); document.write( "8x^2-120x-128=0
\n" ); document.write( "divide by 8
\n" ); document.write( "x^2-15x-16=0
\n" ); document.write( "(x+1)(x-16)=0
\n" ); document.write( "x=-1 (reject, x>0)
\n" ); document.write( "or
\n" ); document.write( "x=16
\n" ); document.write( "ans:
\n" ); document.write( "speed of boat in still water=16 mph \n" ); document.write( "
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