Question

2) Which term of the AP 21, 16, 25. is zero​

Answer 1

the eightth term is zero

Answer 2

$\huge \underline \bold \red {Question}$

Which term of the AP 21, 16, 25. is zero?

$\huge \underline \bold \red {Answer}$

Here Given,

a = 21

d = t2 - t1 = 16 - 21 = - 5

⠀⠀t3 - t2 = 25 - 16 = 11

Common difference is not same.

So, your A. P is wrong.