Find the middle term of the AP 6,13,20,.....,216

1.	Find the middle term of the AP 6,13,20,.....,216
Answer» a = 6 , d = 13-6=7, a^n= 216 , n= ?As we know that,a^ n= a+ (n-1)×d216= 6+(n-1)×7216-6= 7n-7210+7 = 7n217/7=nn=31Thus,the AP contains 31 terms.Therefore,its middle term = 31+1/2= 32/2 =16th term.So, middle term of AP = a + 15 d = 6+15 ×7= 111.

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