A ball is dropped and its first rebound reaches 3 m. Every next rebound reaches 70% of the previous one. Which rebound n is the first one lower than 0.5 m?
Sequences & series worksheet with answers
1.Easy
a₁ = 3r = 0.7ε = 0.5
n =
2.Easy
The geometric sequence aₙ = 3·0.5ⁿ⁻¹ decreases. Find the first index n for which aₙ < 0.2.
a₁ = 3r = 0.5ε = 0.2
n =
3.Medium
Exactly one of the four series diverges. Click it.
A: Σ 1/k²B: Σ (3/5)ᵏC: Σ 1/(k² + 7)D: Σ k!/10ᵏ
- 1A: Σ 1/k²
- 2B: Σ (3/5)ᵏ
- 3C: Σ 1/(k² + 7)
- 4D: Σ k!/10ᵏ
4.Medium
Apply the ratio test to Σk=1∞ (k!)²·5ᵏ/(2k)!. Find L = lim |ak+1/ak|.
ak = (k!)²·5ᵏ/(2k)!
L =
5.Hard
Recognise the series and find its sum: S = Σk=0∞ (−1)ᵏ·22k+1/(2k + 1)!.
ak = (−1)ᵏ·22k+1/(2k + 1)!
S =
6.Hard
Find the coefficient c₃ of (x − 1)³ in the Taylor series of f(x) = 1/x about a = 1.
f(x) = 1/xa = 1k = 3
c₃ =
Answer key
- 1. n = 7
- 2. n = 5
- 3. D: Σ k!/10ᵏ
- 4. L = 1.25
- 5. S = 0.9093
- 6. c₃ = −1
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