Question

Which term of the he AP 15 18,21 is -81 ?

Answer 1

Step-by-step explanation:

ur qn has some sought of error n can never have a negative value!

Answer 2

Answer:

23

Please check your question is should be 81 not

- 81. If it is - 81 then n will be negative which is not possible. I have given the answer according to the correct question.

Step-by-step explanation:

Here a=15

d=3

An=81

n=?

As, An=a+(n-1)d

81=15+(n-1)*3

81=15+3n-3

81= 12+3n

3n= 81-12

n= 69/3

n=23

23 term of this AP is 81