The arithmetic sequence −2, 0, 2, 4, … ends with the term 38. How many terms n does it have?
Sequences & series worksheet with answers
1.Easy
a₁ = −2d = 2aₙ = 38
n =
2.Easy
Find the term a30 of the arithmetic sequence 14, 10, 6, 2, …
a₁ = 14d = −4n = 30
a30 =
3.Medium
Find the sum S = Σk=1∞ 6/(k(k + 3)).
ak = 6/(k(k + 3))
S =
4.Medium
Find the radius of convergence R of the power series Σk=1∞ k·2ᵏ·(x − 3)ᵏ.
Σ k·2ᵏ·(x − 3)ᵏx₀ = 3
R =
5.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 0.001.
f(x) = sin xx = 2M = 1ε = 0.001
n =
6.Hard
Use the Maclaurin polynomial of degree 3 of f(x) = 1/(1 − x) to approximate f(0.5). Give P₃(0.5).
f(x) = 1/(1 − x)n = 3x = 0.5
P₃(0.5) =
Answer key
- 1. n = 21
- 2. a30 = −102
- 3. S = 3.667
- 4. R = 0.5
- 5. n = 9
- 6. P₃(0.5) = 1.875
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