<PRE><B>Question 903887</B>
boat   	speed	x   	mph		Time forward + time return = hours												
current     	speed	3	mph														
																	
against	current     	x-	3	mph													
with	current     	x+	3	mph													
																	
Distance=	40	miles															
																	
Time against + time with  =			14	hours													
t=d/r																	
																	
40	/(	x   	+	3	)	+	40	/(x	-	3	)	=	14				
																	
LCD =	(x	-	3	)	(	x   	+	3	)								
40	*(	x   	-	3	)	+	40	(x	+	3	)	=	14	(x^2	-	9	)
40	x   	-	-120	+	40	x   	+	120		=	14	(	x ^2		-	9	)
80	x   	=	14	x ^2		-126											
14	x ^2	-	-80	x   	-	126	=	0									
																	
Find the roots of the equation by quadratic formula															5.12		
																	
a=	14	,	b=	-80	,	c=	-126										
																	
b^2-4ac=	6400	+	7056														
b^2-4ac=	13456																
{{{	sqrt(	13456	)=	116	}}}							379.94					
{{{x=(-b+-sqrt(b^2-4ac))/(2a)}}}																	0
{{{x1=(-b+sqrt(b^2-4ac))/(2a)}}}																	
x1=(	80	+	116	)/	28												
x1=	7.00																
{{{x2=(-b-sqrt(b^2-4ac))/(2a)}}}																	
x2=(	80	-116	) /	28													
x2=	-1.29																
Ignore negative value																	
boat   	speed	7	mph														
																	
m.ananth@hotmail.ca																	
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