Question

a=11,d=-4,n=11 find sn​

Answer 1

a=11,d=-4,n=11

sn=?

by formula___

$sn = \frac{n}{2} (2a + (n - 1)d)$

=11/2 (2×11+(11-1)(-4))

=11/2 (22-40)

=11/2×(-18)

=-99 Answer.