Question

3, 7, 11, 15, . . . . is an arithmetic sequence a) What is the common difference ? b) Write the 20th term c) Write the algebraic form d) Check whether 261 a term of this sequence

Answer 1

Answer:

a) 4

b) 79

c) 4n - 1

d) No

Step-by-step explanation:

a) Common difference = d = 7 - 3 = 4

b) aₙ = a + (n - 1)d

  ⇒ a₂₀ = 3 + (20 - 1)4

  ⇒ a₂₀ = 3 + 76

  ⇒ a₂₀ = 79

c) aₙ = a + (n - 1)d

⇒ aₙ = 3 + 4n - 4

⇒ aₙ = 4n - 1

d) 261 = 4n - 1

  ⇒ 262 = 4n

  ⇒262/4 = n

∴ Since 262 is not divisible by 4, 261 des not lie in the required AP.