Find the sum of two middle terms of the
a.P -4/3,-1,-2/3,......13/3
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Common difference:
→ - 1 - (- 4/3) = 1/3
→ - 2/3 - (- 1) = 1/3 and so on....
→ 13/3 = - 4/3 + (n - 1)(1/3)
→ 13/3 + 4/3 = (n - 1)/3
→ 17/3 × 3 = n - 1
→ 17 + 1 = n
→ 18 = n
Hence there are 18 terms in A.P.
→ Middle term: 9th term and 10th term
→ 9th term = a + 8d
→ - 4/3 + 8(1/3) = 4/3
→ 10th term = a + 9d
→ - 4/3 + 9(1/3) = 5/3
Sum of 9th and 10th term
→ 4/3 + 5/3 = 9/3
Hence 9/3 is the required answer.
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