<PRE><B>Question 739904</B>
Part I	15.00%		per annum	-------------	Amount invested =x					
Part II	7.00%		per annum	------------	Amount invested = y					
	50000									
Interest-----	6000.00									
										
Part I	15.00%		per annum	---x					*	
Part II	7.00%		per annum	---y						
Total investment										
x	+	1	y=	50000	-------------1					
Interest on both investments										
15.00%	x	+	7.00%	y=	6000					
Multiply by		100								
15	x	+	7	y=	600000.00	--------2				
Multiply (1) by			-15							
we get										
-15	x	-15	y=	-750000.00						
Add this to (2)										
0	x	-8	y=	-150000						
divide by		-8								
			y	=	18750				 -	x)
Part I	15.00%	$	31250							
Part II	7.00%	$	18750							
										
CHECK										
31250	---------	15.00%	-------	4687.50						
18750	-------------	7.00%	-------	1312.50						
Total			--------------------	6000.00						
------------

Boat speed	x	mph											
current speed	3	mph											
													
Distance with wind	24	miles											
Distance against wind	24	miles											
													
spee with current	x	+	3	mph									
speed against	x		3	mph									
Total   time =		6	hours										
Time with current=		24	/(	x	+	25	)						
time against current		24	/	(	x	-25	)						
													
Time with  current + time against  =			10	hours									
													
24	/(	x	+	3	)	+	24	/(x	-3	)	=	6	
LCD =	(	x	+	3	)*	(x	-3	)					
multiply the equation by the LCD													
we get													
24	*	(x	-3	)+	24	(x	+	3	)=	6	(x^2-	9	)
24	x	-72	+	24	x	+	72	)=	6	X^2		54	
48	x	0	=	10	X^2		-54						
6	X^2	-48	x	0	+	-54	=	0					
6	X^2+	-48	x+	-54	=	0							OK
/	1												
6	X^2	-48	x	-54	=	0							
													
	Find the roots of the equation by quadratic formula												
													
	a=	6	b=	-48	c=	-54							
													
	b^2-4ac=	2304	-	-1296									
	b^2-4ac=	3600			{{{sqrt(	3600	)}}}=	60					=
	{{{x=(-b+-sqrt(b^2-4ac))/(2a)}}}												
	{{{x1=(-b+sqrt(b^2-4ac))/(2a)}}}												
	x1=(	48	+	60	)/	12							
	x1=	9											
	x2=(	48	-60	) /	12								
	x2=	-1											
	Ignore negative value			mph									
	x	=	9										
			


							
m.ananth@hotmail.ca										
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