Question

find middle terms of ap 4 ,9,14......149.

Answer 1

hey mate here is your answer......

104=4+(n-1)5
100=(n-1)5
20=n-1
21=n

As n is odd ,
Middle term = n+1/2
=21+1/2
=22/2
=11

11th term = 4+(11-1)5
=4+50
=54

Answer 2

An=a+(n-1)d
Given an=149
Given d=5
Number of terms is equal to
149=4+(n-1)5
149-4=(n-1)5
145/5=n-1
29=n-1
29+1=n
30=n

Therefore number of terms is 30
Middle term is equal to 15

A15=a+14d
A15=4+(14)(5)
A15=74