Question

what term of the A.P. 21,42,63,84,..... is 210?

Answer 1

Hi

Here is your answer

a = 21
d = 42 - 21 = 21
an = 210

an = a + ( n-1)d

210 = 21+ (n-1)21

210 - 21 = 21n - 21

189 = 21n - 21

189 + 21 = 21n

210 = 21n

n = 210/21

n = 10

Hope it helps U

Answer 2

Answer:

10th term.

Step-by-step explanation

Given A.P: 21,42,63,84.....

a=21

d=21(42-21=21 & 63-42=21)

an=210

an=a+(n-1)d

210  =21+(n-1)21

210  =21+21n-21

210  =21n

210/21  =n

10    =n