Find the sum S of the infinite series Σk=0∞ 10·(−1/4)ᵏ.
Sequences & series worksheet with answers
1.Easy
a = 10r = −1/4k₀ = 0
S =
2.Easy
Find the sum S15 of the first 15 terms of the arithmetic sequence 8, 14, 20, 26, …
a₁ = 8d = 6n = 15
S15 =
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
Apply the ratio test to Σk=1∞ kᵏ/(3ᵏ·k!). Find L = lim |ak+1/ak|.
ak = kᵏ/(3ᵏ·k!)
L =
5.Hard
Use the Maclaurin polynomial of degree 2 of f(x) = ln(1 + 2x) to approximate f(−0.2). Give P₂(−0.2).
f(x) = ln(1 + 2x)n = 2x = −0.2
P₂(−0.2) =
6.Hard
f(x) = sin 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 0.0005.
f(x) = sin xx = 2M = 1ε = 0.0005
n =
Answer key
- 1. S = 8
- 2. S15 = 750
- 3. L = 0.5437
- 4. L = 0.9061
- 5. P₂(−0.2) = −0.48
- 6. n = 9
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