Urgent
Q. The sum of first two terms of a geometric progression is 12 and the sum of the third and fourth terms is 48. If the terms of the geometric progression are alternately positive and negative then the first term is
(A) - 4
(B) - 12
(C) 12
(D) 4

Let a be the first term and r be the common ratio.Now, a + ar = 12a1 + r = 12    a = 121+r   ....1Now, ar2 + ar3 = 48ar21 + r = 48121+r× r2 × 1+r = 48r2 = 4r = 2 or  r = -2   rejectedNow, a = 121+r = 121+2 = 4

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