Question

Find the sum of 3, 8, 13, 18.
of first 16 terms​

Answer 1

Answer:

3+8+13+18+23+28+33+38+43+48+53+58+63+68+73+78 = 608

Answer 2

Here a=3

d=5

n=16

We know that sum of an ap

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

So S16=16/2(2x3+(16-1)5)

=8(6x15x5)

=8x450

=3600