The question is followed by two statements, A and B. Answer the questi...
Using statement A alone:
Sum of squares of only two pair of positive integers (i.e. (7, 9) and (3, 11)) is equal to 130.
So the second and third terms can be (7, 9), (9, 7) or (11, 3).
(3, 11) is not possible, as in that case the first term of the AP will become negative.
But still we cannot find exact value of second and third term of an AP. Hence, no conclusion can be drawn about the first term of an AP.
Hence, statement A alone is not sufficient to answer the question.
Using statement B alone: This does not provide any useful information about the first term of the AP. Hence, statement B alone is not sufficient to answer the question.
Using both the statements together:
From statement A it is clear that the second and third terms can be (7, 9), (9, 7) or (11, 3).
The different possible APs are
5, 7, 9, 11, 13, 15,... (possible)
11, 9, 7, 5, 3, 1 (sixth term is not divisible by 3, not possible)
19, 11, 3, -5, -13, -21 (sixth term is not positive, not possible)
Hence, the first term of the AP will be 5.
Hence, question can be answered using both the statements together.
Hence, option 4.
(9, 7) and (11,3) does have negative common difference. But that doesn't mean that these AP will be negative at some point. Because we don't know the number of elements in these series we can't assume them as infinte series or finite series.
AP could be,
11,9, 7 ,..., 1 and 19, 11,3.