Question

If 7 times the 7th term of an arithmetic progression is equal to 11 times to 11 terms .what is 18 term

Answer 1

18th term is 0

____________________

7th Term = a7 = (a + 6d)

11th Term = a11 = (a + 10d)

Given :-

7 times the 7th term is equal to 11 times the 11th term, 7(a7) = 11(a11)

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

7a + 42d = 11a + 110d

7a - 11a = 110d - 42d

-4a = 68d (÷ 4)

-a = 17d

a = -17d

a + 17d = 0

{a + 17d = a18}

a18 = 0

•°• 18th term is 0.