Let the sum of the first n terms of a non-constant A.P., a1, a2, a3, …….. be 50n + n(n - 7/2) A, where A is a constant. If d is the common difference of this A.P., then the ordered pair (d, a50) is equal to :
(1) (50, 50 + 46 A)
(2) (50, 50 + 45 A)
(3) (A, 50 + 45 A)
(4) (A, 50 + 46 A)
