Question

the sum of 16 term of an AP 10,6,2....49

Answer 1

the formula for the sum of first n terms of a AP is n/2(2a+(n-1)d)

here n=16 a=10 d=6-10=2-6=-4

so sum of first 16 terms=16/2(2·10+(16-1)·-4)

=8(20+15·-4)

=8(20-60)

=8(-40)

=-320

Answer 2

this ap is not end with 49 may be its -49 because numbers are decreasing continuously
sn=n/2(2a+(n-1)d)
16/2(2*10+(16-1)-4)
8(20-60)
8(-40)
=-320