Question 445844
Boat speed 	x   		
current speed 	4		
				
against current x-4	mph	
with current x+	4	mph	
				
Distance= 10	miles		
				
Time agianst + time with  = 10	hours
t=d/r				
10/(x +4)+10/(x	-4)=10				
LCD =(x	-4)(x+4)
10*(x-4)+10x+4)=10				
10x-40+10x+40=10(x ^2-16)
20x=10x^2-160								
10x ^2-20x-160	=0
Find the roots of the equation by quadratic formula							
							
a=	10	b=	-20	c=	-160		
							
b^2-4ac=400+6400				
b^2-4ac=6800
sqrt(6800)=82.46
{{{x=(-b+-sqrt(b^2-4ac))/(2a)}}}							
{{{x1=(-b+sqrt(b^2-4ac))/(2a)}}}							
x1=(20+82.46)/20		
x1=5.12						
x2=(20-82.46)/20			
x2= -3.12						
Ignore negative value							
	speed = 5.12 mph