Which term of A.P. 3, 8, 13, 18, ... is 88?

1.	Which term of A.P. 3, 8, 13, 18, ... is 88?
Answer» Here, a = 3, d = 8 – 3 = 5 and a_n = 88 To find : n We have, a_n = a + (n – 1)d ⇒ 88 = 3 + (n – 1) × (5) ⇒ 88 = 3 + 5n – 5 ⇒ 88 = –2 + 5n ⇒88 + 2 = 5n ⇒ 90 = 5n ⇒ n = 18 Therefore, the 18^th term of the given AP is 88.

Answer»

Here, a = 3, d = 8 – 3 = 5 and a_n = 88

To find : n

We have,

a_n = a + (n – 1)d

⇒ 88 = 3 + (n – 1) × (5)

⇒ 88 = 3 + 5n – 5

⇒ 88 = –2 + 5n

⇒88 + 2 = 5n

⇒ 90 = 5n

⇒ n = 18

Therefore, the 18^th term of the given AP is 88.

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