Find the sum S of the infinite series Σk=2∞ 6·(4/5)ᵏ.
Sequences & series worksheet with answers
1.Easy
a = 6r = 4/5k₀ = 2
S =
2.Easy
Find the sum S of the infinite series Σk=0∞ 9·(−1/4)ᵏ.
a = 9r = −1/4k₀ = 0
S =
3.Medium
Find the radius of convergence R of the power series Σk=1∞ xᵏ/3ᵏ.
Σ xᵏ/3ᵏx₀ = 0
R =
4.Medium
The power series Σk=1∞ 5ᵏ·(x − 3)ᵏ/(k + 1) converges on an interval around x₀ = 3. Find the left end x of that interval.
Σ 5ᵏ·(x − 3)ᵏ/(k + 1)x₀ = 3
x =
5.Hard
Find the coefficient c₂ of (x − 4)² in the Taylor series of f(x) = ln x about a = 4.
f(x) = ln xa = 4k = 2
c₂ =
6.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 0.0005.
f(x) = cos xx = 0.5M = 1ε = 0.0005
n =
Answer key
- 1. S = 19.2
- 2. S = 7.2
- 3. R = 3
- 4. x = 2.8
- 5. c₂ = −0.03125
- 6. n = 4
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