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 S of the infinite series Σk=2∞ 4·(−2/5)ᵏ.
a = 4r = −2/5k₀ = 2
S =
3.Medium
Find the sum S = Σk=1∞ 12/(k(k + 2)).
ak = 12/(k(k + 2))
S =
4.Medium
Apply the ratio test to Σk=1∞ k!/kᵏ. Find L = lim |ak+1/ak|.
ak = k!/kᵏ
L =
5.Hard
f(x) = cos x is approximated at x = 2 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) = cos xx = 2M = 1ε = 0.001
n =
6.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 0.0005.
f(x) = eˣx = 2M = 8ε = 0.0005
n =
Answer key
- 1. S = −1.2
- 2. S = 0.4571
- 3. S = 9
- 4. L = 0.3679
- 5. n = 9
- 6. n = 10
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