If the solution curve, of the differential equation dydx= x+y-2x-y passing through the point (2,1) is -1 ( y-1x-1 )- 1 e ( + ( y-1x-1 )2 )= e|x-1|, then 5 + is equal to .
Answer
11
Solution
x+y-2=0 and x-y=0 meet at (1,1): put x=X+1, y=Y+1
dYdX= X+YX-Y (homogeneous); Y=vX:
v+X dvdX= 1+v1-v X dvdX= 1+v21-v
1-v1+v2dv= dXX -1v- 12 (1+v2 )= |X|+C
At (2,1): X=1, v=0 =0
-1 ( y-1x-1 )- 12 e (1+ ( y-1x-1 )2 )= e|x-1|
=1, =2 5 + =11
Answer: 11