Question 535921
Plane speed =	325							
wind speed =	x 																		
																			
Speed with 	wind 	325	+	x 															
Speed against	wind 	325	-	x 															
																			
Distance =	2100 km																		
																			
t=d/r																			
																			
Time against 	wind 	-	Time with	Wind 	=	1	
2100 /(	325-x)-	2100/(325+x  )	=	1									
LCD= 	(	325	-	x)(	325	+	x)												
Multiply equation by LCD																			
We get																			
2100 (	325+x)-	2100(325-x)=1*(325-x)(325+x)
682500+2100x -682500+2100x=1*(	105625	-x^2)						
4200	x 	=105625	-1x^2													
-1	x^2	-4200	x   	+	105625	=	0												
Find the roots of the equation by quadratic formula																			
																			
a=	-1	,b=	-4200	c	105625														
																			
b^2-4ac=	17640000	-	422500																
b^2-4ac=	18062500																		
{{{sqrt(	18062500	)}}}=	4250																
{{{x=(-b+-sqrt(b^2-4ac))/(2a)}}}																			
{{{x1=(-b+sqrt(b^2-4ac))/(2a)}}}																			
x1=(	4200	+	4250	)/	-2														
x1=	-4225																		
x2=(	4200	-4250	) /	-2															
x2= 	25																		
Ignore negative value																			
speed	=	25	mph																
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