Find the sum S8 of the first 8 terms of the geometric sequence 4, −12, 36, …
Sequences & series worksheet with answers
1.Easy
a₁ = 4r = −3n = 8
S8 =
2.Easy
Find the sum S38 of the first 38 terms of the arithmetic sequence −9, −6.5, −4, −1.5, …
a₁ = −9d = 2.5n = 38
S38 =
3.Medium
Find the radius of convergence R of the power series Σk=1∞ 9ᵏx²ᵏ/k.
Σ 9ᵏx²ᵏ/kx₀ = 0
R =
4.Medium
Apply the ratio test to Σk=1∞ (k!)²·2ᵏ/(2k)!. Find L = lim |ak+1/ak|.
ak = (k!)²·2ᵏ/(2k)!
L =
5.Hard
Find the coefficient c₃ of (x − 2)³ in the Taylor series of f(x) = eˣ about a = 2.
f(x) = eˣa = 2k = 3
c₃ =
6.Hard
f(x) = eˣ 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 = 2, find the smallest degree n that guarantees an error below 1 × 10⁻⁶.
f(x) = eˣx = 0.5M = 2ε = 1 × 10⁻⁶
n =
Answer key
- 1. S8 = −6560
- 2. S38 = 1416
- 3. R = 0.3333
- 4. L = 0.5
- 5. c₃ = 1.232
- 6. n = 7
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