Question

Is 7th time the 7th term of an A. P is equal to 11 times the 11term show that the 18th term of an A. P is zero

Answer 1

Answer:

General term of A.P ⇒a

n

=a+(n−1)d

⇒ 7 times 7

th

term = 11 times 11

th

term

⇒7(a+6d)=11(a+10d)

⇒7a+42d=11a+110d

⇒42−110d=11a−7a

⇒−68d=4a

⇒−17d=a ___ (1)

∴18

th

term = a+17d

=−17d+17d (from (1))

=0

∴18

th

term is 0