Find the value of the middle term of the following AP −6,−2,2,.....,58
First we will find the number of terms of the given AP,
Where, Last term =58, a= first term =−6
Here d=−2−(−6)=−2+6=4
Since, an=a+(n−1)d
⇒58=−6+(n−1)4
⇒58=−6+4n−4
⇒58=−10+4n
⇒58+10=4n
⇒68=4n
∴n=17
Since, number of terms is 17.
So middle term will be the 9th term.
We can find 9th term: a9=a+(9−1)×4
=−6+8×4
=32−6=26
So middle term of the above AP is 26