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The first two terms of a geometric progression add up to 12 . The sum of third and fourth terms is 48. If the terms are alternately positive and negative, then

Options

  1. Acommon ratio of G.P. is -2
  2. Bcommon ratio of G.P. is -3
  3. Csixth term of G.P. is 128
  4. Dnone of these

Correct answer

A. common ratio of G.P. is -2

Step-by-step solution

aligned & a+a r=12 ....(1) & a r^2+a r^3=48 ....(2) & r^2=4 r=-2, r -1,2 aligned

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