Question

Write the first three terms of the G.P. whose first term and the common ratio are given below

a = 1000, r = `2/5`

Answer 1

a = 1000, r = `2/5`

t_n = ar^n-1

t₁ = ar^1-1 = ar⁰ = 1000 × 1 = 1000

t₂ = ar^2-1 = ar = `1000 xx 2/5` = 400

t₃ = ar^3-1 = ar² = `1000 (2/5)^2`

= `1000 xx 4/25`

= 160

∴ The 3 terms are 1000, 400, 160, …