Question

Find the A.P. whose nth term is 7 – 3K. Also find the 20th term.

Answer 1

T_n = 7 – 3n
Giving values 1, 2, 3, 4, … to n, we get
T₁ = 7 – 3 x 1 = 7 – 3 = 4
T₂ = 7 – 3 x 2 = 7 – 6 = 1
T₃ = 7 – 3 x 3 = 7 – 9 = -2
T₄ = 7 – 3 x 4 = 7 – 12 = -5
T₂₀ = 7 – 3 x 20 = 7 – 60 = -53
A.P. is 4, 1, -2, -5, …
20th term = -53