2x/(x? - 1)+2x/( 1-x)=2x/(x? - 1)-2x(x+ 1)/(x? - 1)=2x? /( 1-x? )
When x=0, 2x/(x? - 1)+2x/( 1-x)=0
When x=3, 2x/(x? - 1)+2x/( 1-x)=-9/4
2 、[(2x+y )/(x? -2xy+y? )] × (x-y)=[(2x+y )/(x-y)? ]×(x-y)= =(2x+y)/(x-y)
Because x-3y = 0 = "x = 3y.
So [(2x+y )/(x? -2xy+y? )]×(x-y)=(2x+y)/(x-y)=(6y+y)/(3y-y)= 7/2