Find the sum S of the infinite series Σk=1∞ 18·(3/4)ᵏ.
Sequences & series worksheet with answers
1.Easy
a = 18r = 3/4k₀ = 1
S =
2.Easy
Find the sum S10 of the first 10 terms of the geometric sequence 1, −2, 4, …
a₁ = 1r = −2n = 10
S10 =
3.Medium
Apply the ratio test to Σk=1∞ k³·3ᵏ/5ᵏ. Find L = lim |ak+1/ak|.
ak = k³·3ᵏ/5ᵏ
L =
4.Medium
Find the radius of convergence R of the power series Σk=1∞ xᵏ/(k²·3ᵏ).
Σ xᵏ/(k²·3ᵏ)x₀ = 0
R =
5.Hard
Find the coefficient c₃ of (x + 1)³ in the Taylor series of f(x) = e3x about a = −1.
f(x) = e3xa = −1k = 3
c₃ =
6.Hard
Use the Maclaurin polynomial of degree 2 of f(x) = cos x to approximate f(1). Give P₂(1).
f(x) = cos xn = 2x = 1
P₂(1) =
Answer key
- 1. S = 54
- 2. S10 = −341
- 3. L = 0.6
- 4. R = 3
- 5. c₃ = 0.224
- 6. P₂(1) = 0.5
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