1.

Let `{a_n}` bc a G.P. such that `a_4/a_6=1/4` and `a_2+a_5=216`. Then `a_1=`A. `12or,(108)/(7)`B. 10C. `7or,(54)/(7)`D. none of these

Answer» Correct Answer - A
Let r be the common ratio of the G.P. Then,
`(a_(4))/(a_(6))=(1)/(4)rArr(1)/(r^(2))=(1)/(4)rArrr=pm2`
Now,
`a_(2)+a_(5)=216`
`rArr" "a_(1)(r+r^(4))=216`
`rArr" "18a_(1)=216or,14a_(1)=216rArra_(1)=12,(108)/(7)`


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