Which term of the AP 21, 42, 63, 84, ... is 210?
(a) 9th
(b) 10th
(c) 11th
(d) 12th

Open in App

Solution

(b) 10^th

Here, a = 21 and d = (42 - 21) = 21
Let 210 be the n^th term of the given AP.
Then T_n = 210
⇒ a + (n - 1)d = 210
⇒ 21 + (n - 1) ⨯ 21= 210
⇒ 21n = 210
⇒ n = 10
Hence, 210 is the 10^th term of the AP.

Suggest Corrections

Similar questions

9^{t h}

10^{t h}

11^{t h}

12^{t h}

Which term of the AP 25, 20, 15, ... is the first negative term?
(a) 9th
(b) 8th
(c) 7th
(d) 10th

21, 42, 63, 84, . . .

210 ?

Join BYJU'S Learning Program