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0 < 2 - x < 3
0 - 2 < 2 - 2 - x < 3 - 2
- 2 < - x < 1
- 1 < x < 2
((y+1)/(y-1)-y/(y+1))*(3y+1)/(y²+y)=((y+1)²-(y²-y)/(y²-1))*(3y+1)/(y²+y)=
=((y²+2y+1-y²+y)/(y²-1))*(3y+1)/(y²+y)=((3y+1)/(y²-1))*(3y+1)/(y²+y)=
=(3y+1)²/((y-1)(y+1)*y*(y+1))=(3y+1)²/(y*(y+1)²*(y-1)).