Question

9. The sum of first 15 terms of an A.P whose nth term is given by 3+4n*
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Answer 1

First term, a=1,15

th

term a

15

=3−30=−27

Sum of 15 terms =

2

n

(a+l(lastterm))=

2

15

(1−27)=15(−13)=−195