Question

the sum of the first and 16th term of an ap is 140.find the sum of the. 6 and 16th term

Answer 1

Answer:

S14=1050

a=10

Sn=2n[2a+(n−1)d]

1050=214[2×10+(14−1)d]

71050=[20+14d−d]

150−20=13d

130=13d

d=10

The 20th term is

a20=a+(n−1)d

=10+(20−1)10

⇒10+190

a20⇒200