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Question: Answered & Verified by Expert
Let a1, a2, a3,a10 be in G.P. with ai>0  for i=1, 2, , 10 and S be the set of pairs r, k, r, kN (the set of natural numbers) for which

logea1r a2klogea2ra3klogea3ra4klogea4r a5klogea5ra6klogea6ra7klogea7ra8klogea8ra9klogea9ra10k=0

Then the number of elements in S, is:
MathematicsDeterminantsJEE MainJEE Main 2019 (10 Jan Shift 2)
Options:
  • A Infinitely many
  • B 4
  • C 10
  • D 2
Solution:
1663 Upvotes Verified Answer
The correct answer is: Infinitely many
C3C3-C2,  C2C2-C1 ( Let α is common ratio of GP)

logea1ra2klogeαr+klogeαr+klogea4ra5klogeαr+klogeαr+klogea7ra8klogeαr+klogeαr+k=0 which is always true because C2 & C3 are identical.

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