Found on the net. Is procedure wrong in the following equation? Let X=Y or X-Y=0 -----equation (1) Also 2(X-Y)=0 or 2X-2Y=0-----equation (2) Since equation (1) and (2) both are equal on right hand sides Therefore X-Y=2X-2Y or X-Y=2(X-Y) getting rid of (X-Y) on both sides we have 1=2 ?