Question

which term of A. P 21,42,63,84 ___is 210 ​

Answer 1

answer

the 10th term of an AP is 210.

explanation

Let nth term of the given AP be 210

Here, first term, a = 21

and common difference, d = 42 - 21 = 21 and an = 210

∵ an = a + (n-1)d

⇒ 210 = 21 + (n-1)21

⇒ 210 = 21 + 21n - 21

⇒ 210 = 21n ⇒ n = 10

Hence, the 10th term of an AP is 210.

Answer 2

Answer:

10

Step-by-step explanation:

common difference= 42-21=21

general term of A.P.=first term+(term number-1)*(common difference)

210=21+(term number-1)*21

210-21=(term number-1)*21

189/21=(term number-1)

9+1=term number

Hence, term number=10.