Question

The n^th term of a sequence is (2n – 3), find its fifteenth term.

Answer 1

n^th term of A.P = (2n – 3)

`=>` t_n = 2n – 3

n ∈ N

n = 1, 2, 3, .....

a₁ = 2(1) – 3

= –1

a₂ = 2(2) – 3

= 1

a₃ = 2 × 3 – 3

= 6 – 3

= 3

A.P. = –1, 1, 3

a = –1

a = 1 – (–1) = 2

a_n = a + (a – 1)d

a₁₅ = a + (15 – 1)d

a₁₅ = a + 14d

a₁₅ = –1 + 14 × 2

a₁₅ = –1 + 28

a₁₅ = 27