Question 766905
boat   	speed	x   	mph														
current     	speed	3	mph														
																	
against	current     	x-	3	mph													
with	current     	x+	3	mph													
																	
Distance=	91	miles															
																	
Time against + time with  =			20	hours													
t=d/r																	
																	
91	/(	x   	+	3	)	+	91	/(x	-	3	)	=	20				
																	
LCD =	(x	-	3	)	(	x   	+	3	)								
91	*(	x   	-	3	)	+	91	(x	+	3	)	=	20	(x^2	-	9	)
91	x   	-	-273	+	91	x   	+	273		=	20	(	x ^2		-	9	)
182	x   	=	20	x ^2		-180											
20	x ^2	-	-182	x   	-	180											
																	
Find the roots of the equation by quadratic formula																	
			iiiii														
a=	20	,	b=	-182	,	c=	-180										
																	
b^2-4ac=	33124	+	14400														
b^2-4ac=	47524																
{{{	sqrt(	47524	)=	218	}}}												
{{{x=(-b+-sqrt(b^2-4ac))/(2a)}}}																	
{{{x1=(-b+sqrt(b^2-4ac))/(2a)}}}																	
x1=(	182	+	218	)/	40												
x1=	10.00																
{{{x2=(-b-sqrt(b^2-4ac))/(2a)}}}																	
x2=(	182	-218	) /	40													
x2=	-0.90																
Ignore negative value																	
boat   	speed	10	mph														
																	
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