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Nilanjan Bhowmick AIR 3, CSIR NET (Earth Science)
Abhijeet Gaurav
Since a, b, c are in AP 2b = a+c …(i) Since b, c, d are in GP c2 = bd …(ii) Since c, d, e are in HP 2/d = 1/c + 1/e 2/d = (c+e)/ce …(iii) From (ii), d = c2/b Substitute d in (iii) 2b/c2 = (c+e)/ce 2b/c = (c+e)/e (a+c)/c = (c+e)/e ( From (i) ) Cross multiplying, we get ae + ce = c2 + ce ae = c2 So a, c, e are in GP. Hence GP Is the answer.