Question

Someone pls help

1) If 7 times the 7th term of an ap is equal to 11 times the 11th term. Find its 18th term

Answer 1

7(a+(7-1)d)=11(a+(11-1)d)

7(a+6d)=11(a+10d)

7a+42d=11a+110d

7a-11a=110d-42d

-4a=68d

a=-17d...........(1)

now 18th term=a+17d .........(2)

putting the value of a in eqn 2

-17d+17d

that is equal to o