Question

Find the sum of 15 terms of the list of numbers whose nth term is given by an=3+4n

Answer 1

hey mate here is ur answer

a1=3+4=7

a2=3+8=11

a3=3+12=15

..

a=7 , d=4

sn=n/2[2a+(n-1)d]

s15=15/2[14+14×4]

=15/2[70]

=15×35

=525.

hope it helps.

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