Question

Find the sum of 12 terms of an A.P. whose nth term is given by an = 3n + 4
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Answer 1

Answer:

in an A.P.

T(n)=3n+4 putting n=1,2,3,- - - -,we get

7,10,13,16,- - - Are in A.P.

First term a=7,d=3.

S(n)= n/2{2a+ (n-1)d}

s(12) =12/2{2×7+(12–1)3}

=6{14+33}

=6×47

=282.

Answer 2

Hope this helps.....