Question 489600
first part	48	miles										
second part	5	miles										
												
speed in first part	x			mph								
speed second part	x		-5	mph								
Total rowing time		3	hours									
Time first part		48	/	x								
Time second part		5	/	(	x	-5	)					
												
Time first part + time second part =			3	hours								
												
48	/	x				+	5	/(x	-5	)	=	3
LCD =	(	x	+	0	)*	(x	-5	)				
multiply the equation by the LCD												
we get												
48	*	(x	-5	)+	5		x				=	3
48	x	-240	+	5	x				=	3	X^2	
68	x	-240	=	3	X^2							
3	X^2	-68	x	240			=	0				
3	X^2+	-68	x+	240	=							
/	3											
1	X^2	-22.67	x	80	=							
												
Find the roots of the equation by quadratic formula												
												
a=	1	b=	-22.67	c=	80							
												
b^2-4ac=	513.78	-	-320									
b^2-4ac=	193.78			{{{sqrt(	193.78	)}}}=	13.92					
{{{x=(-b+-sqrt(b^2-4ac))/(2a)}}}												
{{{x1=(-b+sqrt(b^2-4ac))/(2a)}}}												
x1=(	22.67	+	13.92	)/	2							
x1=	18.29		18 2/7									
x2=(	22.67	-13.92	) /	2								
x2= 	4.37		4 3/8									
Ignore negative value												
x	=	18.29	mph		speed	& 5 less in the second part					
												
CHECK												
Time first part	+	Time second part										
2.62	+	0.38	=	3