The geometric sequence aₙ = 8·0.7ⁿ⁻¹ decreases. Find the first index n for which aₙ < 0.05.
Sequences & series worksheet with answers
1.Easy
a₁ = 8r = 0.7ε = 0.05
n =
2.Easy
Find the sum S of the infinite series Σk=1∞ 3·(4/5)ᵏ.
a = 3r = 4/5k₀ = 1
S =
3.Medium
Exactly one of the four series converges. Click it.
A: Σ 5/kB: Σ k²/3ᵏC: Σ k!/2ᵏD: Σ k/(k + 9)
- 1A: Σ 5/k
- 2B: Σ k²/3ᵏ
- 3C: Σ k!/2ᵏ
- 4D: Σ k/(k + 9)
4.Medium
Exactly one of the four series diverges. Click it.
A: Σ k!/10ᵏB: Σ 2ᵏ/k!C: Σ 2/k⁴D: Σ (−1)ᵏ/√k
- 1A: Σ k!/10ᵏ
- 2B: Σ 2ᵏ/k!
- 3C: Σ 2/k⁴
- 4D: Σ (−1)ᵏ/√k
5.Hard
Find the coefficient c₃ of (x − 4)³ in the Taylor series of f(x) = 1/x about a = 4.
f(x) = 1/xa = 4k = 3
c₃ =
6.Hard
Use the Maclaurin polynomial of degree 3 of f(x) = e3x to approximate f(0.8). Give P₃(0.8).
f(x) = e3xn = 3x = 0.8
P₃(0.8) =
Answer key
- 1. n = 16
- 2. S = 12
- 3. B: Σ k²/3ᵏ
- 4. A: Σ k!/10ᵏ
- 5. c₃ = −0.003906
- 6. P₃(0.8) = 8.584
Full step-by-step solutions: practise this topic on examproblems.com.