Which term of the A.P. 84, 80, 76,… is 0 ?
Given A.P is 84, 80, 76,…
Here, a1 = a = 84, a2 = 88
Common difference, d = a2 – a1 = 80 – 84 = -4
We know, an = a + (n – 1)d where a is first term or a1 and d is common difference
∴ an = 84 + (n – 1)-4
⇒ an = 84 – 4n + 4
⇒ an = 88 – 4n
Now, to find which term of A.P is 0
Put an = 0
∴ 88 – 4n = 0
⇒ -4n = -88
⇒ n = 22
Hence, 22th term of given A.P is 0