Find the sum S33 of the first 33 terms of the arithmetic sequence −6, −10, −14, −18, …
Sequences & series worksheet with answers
1.Easy
a₁ = −6d = −4n = 33
S33 =
2.Easy
A ball is dropped and its first rebound reaches 3 m. Every next rebound reaches 60% of the previous one. Which rebound n is the first one lower than 0.01 m?
a₁ = 3r = 0.6ε = 0.01
n =
3.Medium
Apply the root test to Σk=1∞ ((5k + 5)/(2k + 4))ᵏ. Find L = lim |ak|1/k.
ak = ((5k + 5)/(2k + 4))ᵏ
L =
4.Medium
Apply the ratio test to Σk=1∞ 3ᵏ·k!/kᵏ. Find L = lim |ak+1/ak|.
ak = 3ᵏ·k!/kᵏ
L =
5.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 0.0005.
f(x) = eˣx = 0.5M = 2ε = 0.0005
n =
6.Hard
Use the Maclaurin polynomial of degree 2 of f(x) = cos(2x) to approximate f(−0.5). Give P₂(−0.5).
f(x) = cos(2x)n = 2x = −0.5
P₂(−0.5) =
Answer key
- 1. S33 = −2310
- 2. n = 13
- 3. L = 2.5
- 4. L = 1.104
- 5. n = 5
- 6. P₂(−0.5) = 0.5
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