Question

29. Find the sum of first 25 terms of the AP 30, 26, 22. ... .
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Answer 1

Answer:

- 450

Step-by-step explanation:

First term = a = 30

Comm, Diff. = 26 - 30 = - 4

 Using, Sₙ = (n/2) [2a + (n - 1)d] , where n is the number of terms.

S₂₅ = (25/2) [2(30) + (25 - 1)(-4) ]

S₂₅ = (25/2) [60 - 96]

      = (25/2) (-36)

      = -450

Sum of 25 terms of this AP is - 450