Question

which term of a.p21,18,15,....is-81?

Answer 1

$Heya$‼


A.P. :- 21, 18, 15, .....

First term, a = 21

Common difference, d = a2 – a1
= 18 – 21
= –3

As we know,
aⁿ = a + ( n – 1 ) d

–81 = 21 + ( n – 1 ) –3

–81 – 21 = ( n – 1 ) –3

–102 = ( n – 1 ) –3

n – 1 = –102 / –3

n – 1 = 34

n = 34 + 1

n = 35


Therefore, 35th term of given A.P. is –81.

Answer 2

the term of 35 is 81