The arithmetic sequence 19, 17, 15, 13, … ends with the term −7. How many terms n does it have?
Sequences & series worksheet with answers
1.Easy
a₁ = 19d = −2aₙ = −7
n =
2.Easy
Find the sum S of the infinite series Σk=1∞ 4·(1/4)ᵏ.
a = 4r = 1/4k₀ = 1
S =
3.Medium
Find the radius of convergence R of the power series Σk=1∞ xᵏ/(k²·3ᵏ).
Σ xᵏ/(k²·3ᵏ)x₀ = 0
R =
4.Medium
Find the sum S = Σk=1∞ 5/(k(k + 2)).
ak = 5/(k(k + 2))
S =
5.Hard
Use the Maclaurin polynomial of degree 5 of f(x) = sin x to approximate f(2.5). Give P₅(2.5).
f(x) = sin xn = 5x = 2.5
P₅(2.5) =
6.Hard
f(x) = eˣ is approximated by its Maclaurin polynomial of degree 4 at x = 0.8. Use the Lagrange error bound M·|x|ⁿ⁺¹/(n + 1)! with M = e0.8 = 2.226 to find the largest possible error |R₄|.
f(x) = eˣn = 4x = 0.8M = 2.226
|R₄| =
Answer key
- 1. n = 14
- 2. S = 1.333
- 3. R = 3
- 4. S = 3.75
- 5. P₅(2.5) = 0.7096
- 6. |R₄| = 0.006077
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