1.

If the `2^(nd), 5^(th) and 9^(th)` terms of a non-constant A. P. are in G.P, then the common ratio of this G. P. isA. `(8)/(5)`B. `(4)/(3)`C. 1D. `(7)/(4)`

Answer» Correct Answer - B
Let a be the first term and d be the common difference of the A.P. It is given that
`a_(2)=a+d,a_(5)=a+4danda_(9)=a+8d` are in G.P.
`:." "a_(5)^(2)=a_(2)xxa_(9)`
`rArr" "(a+4d)^(2)=(a+d)(a+8d)`
`rArr" "a=8d`
`:." "a_(2)=9d,a_(5)=12d,a_(9)=16d`
The common ratio of the G.P. `(a_(5))/(a_(2))=(12d)/(9d)=(4)/(3)`.


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