Math, asked by prachi4, 1 year ago

which term of the AP 21,42,63,84,...........is 420

Answers

Answered by Ramcharan
219
a=21
d=21
 a_{n} =420
n=?
 a_{n} =a+(n-1)d
420=21+(n-1)21
(n-1)*21=399
n-1=399/21
n-1=19
n=19+1=20
ans..therefore the 20th term of the AP is 420
Answered by Jaizah15
126
an = 420
a = 21 
d = 21
an = a+(n-1)d
420= 21+(n-1)21
399 = (n-1)21
399/21 = (n-10
19 = n-1
19+1 = n
20 = n
20th term is 420
plzz best
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