Question

Find the sum of first 15multiples of 8

Answer 1

Answer:

AP:8,16,24,.........

a=8

d=16-8=8

n=15

Sn=n/2(2a+(n-1)d)

S15=15/2(2*8+(15-1)8

=15/2(16+(14)8)

=15/2(16+112)

=15/2*128

=15*64

=960.

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