Geometric sequences Problem set B Answers

1. (a) 8748
2. (b) 448
3. (c) 1.125

1. (a) \(r = 4,\ u_1 = 3\)
2. (b) \(r = 3,\ u_1 = 2\) or \(r = -3,\ u_1 = 2\)

1. (a) \(2 \times 5^{n-1}\)
2. (b) \(81 \times \left(\tfrac{1}{3}\right)^{n-1}\)

1. (a) 8
2. (b) The 9th term, 13 122

\(5 \times 0.6^4 = 0.648\) m

(a) \(6500 \times 1.035^9 \approx 8860\) (b) 13 years

$19 966.74 (about $20 000)

(a) $40 344.00 (b) 4 years

\((x+6)^2 = x(x+24)\) gives \(x = 3\); the terms are 3, 9, 27 and \(r = 3\).