Question

Find the sum of 11 term of the Ap whose middle term is 30​

Answer 1

Answer:

If there are 11 term, then the middle term will be 6

i.e a₆=30

= a+5d=30                                                     (1)

= S₁₁= 11/2 (2a+10d)

= S₁₁= 11/2 × 2(a+5d)  

= S₁₁= 11 × a+5d

= S₁₁= 11 × 30                                                  (using 1)

= S₁₁= 330