A ball is dropped and its first rebound reaches 5 m. Every next rebound reaches 80% of the previous one. Which rebound n is the first one lower than 0.05 m?
Sequences & series worksheet with answers
1.Easy
a₁ = 5r = 0.8ε = 0.05
n =
2.Easy
The arithmetic sequence −7, −11, −15, −19, … ends with the term −147. How many terms n does it have?
a₁ = −7d = −4aₙ = −147
n =
3.Medium
Apply the ratio test to Σk=1∞ (k!)²·1ᵏ/(2k)!. Find L = lim |ak+1/ak|.
ak = (k!)²·1ᵏ/(2k)!
L =
4.Medium
Exactly one of the four series diverges. Click it.
A: Σ (3/5)ᵏB: Σ 1/(k² + 5)C: Σ (1 + 1/k)ᵏD: Σ (−1)ᵏ/k
- 1A: Σ (3/5)ᵏ
- 2B: Σ 1/(k² + 5)
- 3C: Σ (1 + 1/k)ᵏ
- 4D: Σ (−1)ᵏ/k
5.Hard
Recognise the series and find its sum: S = Σk=1∞ k·(1/3)ᵏ.
ak = k·(1/3)ᵏ
S =
6.Hard
f(x) = sin x is approximated by its Maclaurin polynomial of degree 4 at x = 0.2. Use the Lagrange error bound M·|x|ⁿ⁺¹/(n + 1)! with M = 1 to find the largest possible error |R₄|.
f(x) = sin xn = 4x = 0.2M = 1
|R₄| =
Answer key
- 1. n = 22
- 2. n = 36
- 3. L = 0.25
- 4. C: Σ (1 + 1/k)ᵏ
- 5. S = 0.75
- 6. |R₄| = 2.667 × 10⁻⁶
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