<PRE><B>Question 548366</B>
boat speed	x	mph																	
current speed downstream	2	mph																	
current speed upstream	1																		
Distance with current	2	miles																	
Distance against current	4	miles																	
																			
speed with current	x	+	2	mph															
speed against current	x		1	mph															
Total   time =		3	hours																
Time with current=		2	/(	x	+	2	)												
time against current 		4	/	(	x	-1	)												
																			
Time with  current + time against  =			3	hours															
																			
2	/(	x	+	2	)	+	4	/(x	-1	)	=	3							
LCD =	(	x	+	2	)*	(x	-1	)											
multiply the equation by the LCD																			
we get																			
2*(x-1)+4(x+2)=3(x^2+1x-2)
2x-2+4x+8=3X^2+	3x-6			
6x+6=3x^2+3x+-6								
3x^2-3x	-12=	0											
3x^2-3x-12	=	0													
/	3																		
1	X^2	-1	x	-4	=	0													
																			
	Find the roots of the equation by quadratic formula			 
	a=	1	,b=	-1	,c=	-4													
																			
	b^2-4ac=	1	+	16															
	b^2-4ac=	17																	
	{{{x=(-b+-sqrt(b^2-4ac))/(2a)}}}							4.12											
	{{{x1=(-b+sqrt(b^2-4ac))/(2a)}}}																		
	{{{x1=(-12+21)/(2)}}}																		
	x1=(	1	+	4.12	)/	2													
	x1=	2.56																	
	x2=(	1	-4.12	) /	2														
	x2= 	-1.56																	
	Ignore negative value																		
	boat speed	=	2.56	mph															
	m.ananth@hotmail.ca																		
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