A ball is dropped and its first rebound reaches 20 m. Every next rebound reaches 70% of the previous one. Which rebound n is the first one lower than 0.1 m?
Sequences & series worksheet with answers
1.Easy
a₁ = 20r = 0.7ε = 0.1
n =
2.Easy
The arithmetic sequence 11, 12.5, 14, 15.5, … ends with the term 66.5. How many terms n does it have?
a₁ = 11d = 1.5aₙ = 66.5
n =
3.Medium
Exactly one of the four series diverges. Click it.
A: Σ k/2ᵏB: Σ 1/(k(k + 2))C: Σ 5/k³D: Σ (7/4)ᵏ
- 1A: Σ k/2ᵏ
- 2B: Σ 1/(k(k + 2))
- 3C: Σ 5/k³
- 4D: Σ (7/4)ᵏ
4.Medium
Apply the root test to Σk=1∞ ((5k + 3)/(3k + 1))ᵏ. Find L = lim |ak|1/k.
ak = ((5k + 3)/(3k + 1))ᵏ
L =
5.Hard
f(x) = cos x is approximated by its Maclaurin polynomial of degree 3 at x = 0.3. Use the Lagrange error bound M·|x|ⁿ⁺¹/(n + 1)! with M = 1 to find the largest possible error |R₃|.
f(x) = cos xn = 3x = 0.3M = 1
|R₃| =
6.Hard
Recognise the series and find its sum: S = Σk=0∞ (−1)ᵏ·1.22k/(2k)!.
ak = (−1)ᵏ·1.22k/(2k)!
S =
Answer key
- 1. n = 16
- 2. n = 38
- 3. D: Σ (7/4)ᵏ
- 4. L = 1.667
- 5. |R₃| = 0.0003375
- 6. S = 0.3624
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