Find the term a15 of the arithmetic sequence −4, 0, 4, 8, …
Sequences & series worksheet with answers
1.Easy
a₁ = −4d = 4n = 15
a15 =
2.Easy
Find the sum S10 of the first 10 terms of the geometric sequence 2, −4, 8, …
a₁ = 2r = −2n = 10
S10 =
3.Medium
Find the sum S = Σk=1∞ 4/(k(k + 3)).
ak = 4/(k(k + 3))
S =
4.Medium
Find the radius of convergence R of the power series Σk=1∞ (2k)!·xᵏ/(k!)².
Σ (2k)!·xᵏ/(k!)²x₀ = 0
R =
5.Hard
Recognise the series and find its sum: S = Σk=1∞ k·0.25ᵏ.
ak = k·0.25ᵏ
S =
6.Hard
f(x) = sin x is approximated at x = 1 by its Maclaurin polynomial of degree n. With the Lagrange bound M·|x|ⁿ⁺¹/(n + 1)! and M = 1, find the smallest degree n that guarantees an error below 0.0005.
f(x) = sin xx = 1M = 1ε = 0.0005
n =
Answer key
- 1. a15 = 52
- 2. S10 = −682
- 3. S = 2.444
- 4. R = 0.25
- 5. S = 0.4444
- 6. n = 6
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