Find the sum S of the infinite series Σk=1∞ 12·(1/4)ᵏ.
Sequences & series worksheet with answers
1.Easy
a = 12r = 1/4k₀ = 1
S =
2.Easy
Find the sum S of the infinite series Σk=1∞ 10·(1/2)ᵏ.
a = 10r = 1/2k₀ = 1
S =
3.Medium
Find the sum S = Σk=126 12/(k(k + 1)).
ak = 12/(k(k + 1))n = 26
S =
4.Medium
Find the radius of convergence R of the power series Σk=1∞ 3ᵏ·xᵏ/(k + 1).
Σ 3ᵏ·xᵏ/(k + 1)x₀ = 0
R =
5.Hard
f(x) = cos x is approximated at x = 0.5 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 1 × 10⁻⁶.
f(x) = cos xx = 0.5M = 1ε = 1 × 10⁻⁶
n =
6.Hard
Recognise the series and find its sum: S = Σk=1∞ k·(−0.5)ᵏ.
ak = k·(−0.5)ᵏ
S =
Answer key
- 1. S = 4
- 2. S = 10
- 3. S = 11.56
- 4. R = 0.3333
- 5. n = 7
- 6. S = −0.2222
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