Question

Find the middle term of the A.P., -11 , -7 , -3 , ……………. , 45.

Answer 1

Hi friend ,
here a= -11
        a2= -7
        a3= -3
so d= a2- a
       = -7+11
       = 4
also $a_{n}$= a+ (n-1)d
                             45= -11+(n-1)4
                             45= -11 + 4n-4
                             45=4n-15
                      45+15 =4n
                             60= 4n 
                             15=n
So, It means the Given AP have odd no. of terms
so, the middle term is the 8th term
applying the formula as:-
$a_{n}$= -11 + (8-1)4
$a_{n}$=-11 +28
$a_{n}$=17
So the middle term is 17.
________________________________________________Thanks :)______

Answer 2

hope it's clear now!
thank you