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Let {tn} be a sequence of integers in G....

Let `{t_n}` be a sequence of integers in G.P. in which `t_4: t_6=1:4 and t_2+t_5=216.` Then `t_1` is (a).`12` (b). `14` (c). `16` (d). none of these

A

12

B

14

C

16

D

none of these

Text Solution

Verified by Experts

The correct Answer is:
A
`t_(4)/t_(6)=1/4rArr(ar^(3))/(ar^(5))=1/4rArrr^(2)=4rArrr^(2)=4rArrr=pm2`
Also,`t_(2)+t_(5)=216`
`rArrar+ar^(4)=216`
`rArra+8a=108`
`rArra=a=12` (when r= 2)
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