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Question
Find the indicated terms in each of the following sequences whose nth terms are
an = n (n −1) (n − 2); a5 and a8
Solution
Here, we are given the nth term for various sequences. We need to find the indicated terms of the A.P.
an = n (n −1) (n − 2)
We need to find `a_5` and `a_8`
Now to `a_5` term we use n = 5 we get
`a_5 = 5(5 - 1)(5 - 2)`
= 5(4)(3)
= 60
Also to find `a_8` term we use n = 8 we get
`a_8 = (8(8 - 1)(8 - 2))`
= 8(7)(6)
= 336
Thus `a_5 = 60 and a_8 = 336`
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