Question 665713
speed	x					
speed	x	+	10			
						
Distance = same		75	km   		
original time – time with increased speed =0.25	hour
t=d/t						
75/x-75/(x+10)=	0.25					
LCD=	x	(	x	+	10	)											
multiply by LCD																	
75(x+10)-75x=0.25x(x+10)	
75x+750	-75x=0.25X^2+2.5x					
750=0.25X^2+2.5x											
0.25X^2	+2.5x-750	=0								
Find roots of the quadratic equation																	
a=	0.25		b=	2.5		c=	-750										
																	
x1=(-2.5+sqrt(6.25-750))/0.5						
x1=(	-2.5	+	27.5	)/	0.5												
x1=	50																
																	
x2=(-7-sqrt(49-20)/2						
x2=(	-2.5	-	27.5	)/	0.5												
x2=	-60																
Speed cannot be negative. 

x= 50 km/h

m.ananth@hotmail.ca