Hi (again )
Both the numerator and the denominator of the fraction have been multiplied by . How could you've seen this ? Take a look at the denominator : it was and it becomes hence it has been multiplied by . So that the new fraction equals the old one, one has to multiply the numerator of the old one by too. It can be checked that this was done by computing
Thus what happened is that the whole fraction has been multiplied by .