Question

Check whether – 140 is a term of the AP : 11, 8, 5, 2 …..

Answer 1

first term a = 11
common difference d = -3
now let nth term be -140
therefore
a+(n-1)d = -140
11+(n-1) (-3) = -140
11-3n +3 = -140
-3n = -140-14
-3n=-154
3n= 154
n = 51.33
since n is. an irrational no. and the term cannot be an irrational...
hence -140 is not the term of the given AP...

hope this helps u:p

Answer 2

Nice question.
Answer explained below.
Comment below if any doubt occurs to you.