The arithmetic sequence −2, 0, 2, 4, … ends with the term 48. How many terms n does it have?
Sequences & series worksheet with answers
1.Easy
a₁ = −2d = 2aₙ = 48
n =
2.Easy
Find the sum S of the infinite series Σk=2∞ 6·(−1/3)ᵏ.
a = 6r = −1/3k₀ = 2
S =
3.Medium
Apply the ratio test to Σk=1∞ (k!)²·5ᵏ/(2k)!. Find L = lim |ak+1/ak|.
ak = (k!)²·5ᵏ/(2k)!
L =
4.Medium
Find the radius of convergence R of the power series Σk=1∞ xᵏ/(k²·2ᵏ).
Σ xᵏ/(k²·2ᵏ)x₀ = 0
R =
5.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 =
6.Hard
Find the coefficient c₄ of (x − 3)⁴ in the Taylor series of f(x) = 1/x about a = 3.
f(x) = 1/xa = 3k = 4
c₄ =
Answer key
- 1. n = 26
- 2. S = 0.5
- 3. L = 1.25
- 4. R = 2
- 5. n = 4
- 6. c₄ = 0.004115
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