Find the sum S6 of the first 6 terms of the geometric sequence 0.5, 0.25, 0.125, …
Sequences & series worksheet with answers
1.Easy
a₁ = 0.5r = 0.5n = 6
S6 =
2.Easy
A ball is dropped and its first rebound reaches 8 m. Every next rebound reaches 75% of the previous one. Which rebound n is the first one lower than 0.2 m?
a₁ = 8r = 0.75ε = 0.2
n =
3.Medium
Apply the ratio test to Σk=1∞ kᵏ/(5ᵏ·k!). Find L = lim |ak+1/ak|.
ak = kᵏ/(5ᵏ·k!)
L =
4.Medium
Apply the root test to Σk=1∞ ((3k + 2)/(2k + 5))ᵏ. Find L = lim |ak|1/k.
ak = ((3k + 2)/(2k + 5))ᵏ
L =
5.Hard
Find the coefficient c₂ of (x − 5)² in the Taylor series of f(x) = 1/x about a = 5.
f(x) = 1/xa = 5k = 2
c₂ =
6.Hard
Recognise the series and find its sum: S = Σk=0∞ 0.5ᵏ/k!.
ak = 0.5ᵏ/k!
S =
Answer key
- 1. S6 = 0.9844
- 2. n = 14
- 3. L = 0.5437
- 4. L = 1.5
- 5. c₂ = 0.008
- 6. S = 1.649
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