Find the sum S of the infinite series Σk=1∞ 6·(−1/4)ᵏ.
Sequences & series worksheet with answers
1.Easy
a = 6r = −1/4k₀ = 1
S =
2.Easy
Find the sum S9 of the first 9 terms of the geometric sequence 0.5, 0.4, 0.32, …
a₁ = 0.5r = 0.8n = 9
S9 =
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
Find the sum S = Σk=1∞ 3/(k(k + 1)).
ak = 3/(k(k + 1))
S =
5.Hard
f(x) = eˣ is approximated at x = 2 by its Maclaurin polynomial of degree n. With the Lagrange bound M·|x|ⁿ⁺¹/(n + 1)! and M = 8, find the smallest degree n that guarantees an error below 0.0001.
f(x) = eˣx = 2M = 8ε = 0.0001
n =
6.Hard
f(x) = sin 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 0.001.
f(x) = sin xx = 0.5M = 1ε = 0.001
n =
Answer key
- 1. S = −1.2
- 2. S9 = 2.164
- 3. L = 0.5437
- 4. S = 3
- 5. n = 11
- 6. n = 4
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