1.

The sixth term of an A.P. is equal to 2. The value of the common difference of the A.P. which makes the product a_1 a_4 a_5 least is given by :

Answer»

`8/5`
`4/5`
`2/3`
NONE of these

SOLUTION :`a+5d=2 , P=a_1a_4a_5`
=a(a+3d)(a+4d)
=(2-5d) (2-2d)(2-d)
`P=2(4-16d+17d^2-5d^3)`
`P=2(-16 + 34d-15d^2)=0`
`d=2/3` and `8/5`
For LEAST product d=2/3


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