Q9 of 180 Page 3

If the nth term of AP -2, 5, 12, … is 89, then value of n is

We know that, nth term of an AP is

a_n = a + (n – 1)d, where

a= first term and d = common difference

Here,

First term, a = -2

Common difference, d = a₂ – a₁ = 5 – (-2) = 7

nth term, a_n = 89

To find: n

Putting values, we get

⇒ 89 = -2 + (n – 1)7

⇒ 91 = (n – 1)7

⇒ n – 1 = 13

⇒ n = 14

Hence, Option B is correct.

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