Question

If 7 times the 7th term of an AP is equal to 11 times its 11th term, then its 18th term will be ______.

Options

• 7

• 11

• 18

• 0

Answer 1

If 7 times the 7th term of an AP is equal to 11 times its 11th term, then its 18th term will be 0.

Explanation:-

According to question

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

⇒ 7a + 42d = 11a + 110d

⇒ 4a + 68d = 0

⇒ 4(a + 17d) = 0

⇒ a + 17d = 0

⇒ a = -17d

Therefore,

a₁₈ = a + 17d

a₁₈ = -17d + 17d = 0