Question 565327
Second part x	x	mph 	80	miles						
First part x+	20	mph 	150	miles						
Time first part +Time second part =				4	hours					
150	/	(x 		20	)+	80	/x=	4		
Multiply equation by the LCD			(x+	20	)x 					
150	x+	80	(x+	20	)=	4				
150	x+	80	x+	1600	=	4	(x+	20	)*x	
150	x+	80	x+	1600	=	4	X^2	+	80	x
4	X^2	-150	x 	-1600	=	0				
Find the roots of the equation by quadratic formula										
										
a=	4	,	b=	-150	,	c=	-1600			
										
b^2-4ac=	22500	+	25600							
b^2-4ac=	48100		{{{	sqrt(	48100	)=	219.32	}}}		
{{{x=(-b+-sqrt(b^2-4ac))/(2a)}}}										
{{{x1=(-b+sqrt(b^2-4ac))/(2a)}}}										
x1=(	150	+	219.32	)/	8					
x1=	46.16									
x2=(	150	-219.32	) /	8						
x2= 	-8.66									
Ignore negative value										
=	46.16	mph	speed	in second part

66.16 mph in first part
					
										
m.ananth@hotmail.ca