Question 549686
let going speed be x mph

returning speed = x-96

d= 400
time difference = 2hours

400/(x-96) -400/x=2

LCD = x(x-96)
400x-400x+38400=2x^2-192x
2x^2-192x-38400=0

Find the roots of the equation by quadratic formula					
					
a=	2	,b=	-192	,c=	-38400
					
b^2-4ac=	36864	-	307200		
b^2-4ac=	344064				
{{{sqrt(	344064	)}}}=	586.57		
{{{x=(-b+-sqrt(b^2-4ac))/(2a)}}}					
{{{x1=(-b+sqrt(b^2-4ac))/(2a)}}}					
x1=(	192	+	586.57	)/	4
x1=	194.64				
x2=(	192	-586.57	) /	4	
x2= 	-98.64				
Ignore negative value					
speed	=	194.64	mph		
m.ananth@hotmail.ca