Find the sum of 25 th term of an AP which n the term is given by tn=7-

1.	Find the sum of 25 th term of an AP which n the term is given by tn=7-3n ???
Answer» tn= 7 - 3n t1 =7-3 (1) =4t25 = 7- 3 (25) =7 - 75 = -68Sn = n/2 [t1 + t25]S25= 25/2 [4+(-68)] = 25/2 [-64] = 25 × (-32) = -800

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