How many possible values of (p + q + r) are there satisfying 1/p + 1/q + 1/r = 1, where p, q and r are natural numbers (not necessarily distinct)?

उत्तर देखें और व्याख्या

उत्तर: (C) Three

व्याख्या

The solutions are (3, 3, 3), (2, 4, 4) and (2, 3, 6), giving sums 9, 10 and 11: three values. (Answer as per the official UPSC answer key.)