Comment by slevin063

A1 and A2 have different limits. It will be clear if the upper limit is changed to something other than infinity. Lets say A1 is sum of 1/x, x=1 to 10. For A1 and A2 to be equal, A2 will have limits x=1 to 5. Thus, you cannot strike of sum of (1/x) on both sides in the equation, A1=D.