Question

The nth term of an arithmetic sequence is 3-5n?Write first term and common difference? What is(n+1)th term?Write the(n-1)th term?

Answer 1

write first term and common difference

Answer 2

The answer are First term of series = -2 and common difference d = - 5

(n+1)th term  = -2 - 5n and (n-1)th term = - 5n -2  

Given: nth term of an arithmetic sequence is 3- 5n

To find: first term and common difference

(n+1)th  and (n-1)th term  

Solution:

Given nth term = 3- 5n

To find 1st term take n = 1

⇒ first term of sequence = 3 - 5(1) =3 - 5 = -2

∴ First term of series = -2

To find common difference we need to know 2nd term

⇒ 2nd term of sequence = 3 - 5(2) = 3 - 10 = -7

⇒ common difference = 2nd term - 1st term = -7-(-2) = -7 + 2 = - 5

∴ common difference d = - 5

(n+1)th term = 3- 5 (n+1) = 3 - 5n - 5 = -2 - 5n

(n-1)th term = 3 - 5(n-1) = 3 - 5n -5 = - 5n -2  

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