Find the sum S of the infinite series Σk=1∞ 8·(−2/3)ᵏ.
Sequences & series worksheet with answers
1.Easy
a = 8r = −2/3k₀ = 1
S =
2.Easy
A ball is dropped and its first rebound reaches 3 m. Every next rebound reaches 90% of the previous one. Which rebound n is the first one lower than 0.2 m?
a₁ = 3r = 0.9ε = 0.2
n =
3.Medium
Find the radius of convergence R of the power series Σk=1∞ (x − 2)ᵏ/(k·(1/2)ᵏ).
Σ (x − 2)ᵏ/(k·(1/2)ᵏ)x₀ = 2
R =
4.Medium
Apply the ratio test to Σk=1∞ (k!)²·3ᵏ/(2k)!. Find L = lim |ak+1/ak|.
ak = (k!)²·3ᵏ/(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
Recognise the series and find its sum: S = Σk=1∞ (−1)k+1·0.5ᵏ/k.
ak = (−1)k+1·0.5ᵏ/k
S =
Answer key
- 1. S = −3.2
- 2. n = 27
- 3. R = 0.5
- 4. L = 0.75
- 5. S = 0.9093
- 6. S = 0.4055
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