Question

*Which term of the AP 21, 18, 15, ... , is zero?*

1️⃣ 7
2️⃣ 8
3️⃣ 9
4️⃣ 6​

Answer 1

$\huge\underline\mathbb\blue{Answer}$

Given :-

a1 = 21

d = -3

an = 0

To find :-

n = ?

Solution :-

an = a + (n-1)d

0 = 21 + (n-1)(-3)

0 = 21 - 3n +3

0 = 24 - 3n

3n = 24

n = 24/3

n = 8

Hence option 2️⃣ is correct

Answer 2

Answer:

2️⃣ 8

Step-by-step explanation:

8 is right answer...