Question

which term of A. P. 21, 18 ,15......is zero ​

Answer 1

Answer:

a = 21

d = 13

an = 0

an = a + (n-1) d

0 = 21 + ( n - 1) -3

-21/-3 = n - 1

7+1 = n

n = 8

Answer 2

Answer:

8 term is zero

Step-by-step explanation:

an=0, a=21, d=-3

an = a+(n-1) d

0=21+(n-1)-3

0=21-3n+3

0= 24-3n

-24=-3n

n=8

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