The arithmetic sequence −8, −5, −2, 1, … ends with the term 43. How many terms n does it have?
Sequences & series worksheet with answers
1.Easy
a₁ = −8d = 3aₙ = 43
n =
2.Easy
Find the sum S7 of the first 7 terms of the geometric sequence 10, 5, 2.5, …
a₁ = 10r = 0.5n = 7
S7 =
3.Medium
Apply the ratio test to Σk=1∞ (k!)²·8ᵏ/(2k)!. Find L = lim |ak+1/ak|.
ak = (k!)²·8ᵏ/(2k)!
L =
4.Medium
The power series Σk=1∞ (2k)!·(x − 1)ᵏ/(k!)² converges on an interval around x₀ = 1. Find the right end x of that interval.
Σ (2k)!·(x − 1)ᵏ/(k!)²x₀ = 1
x =
5.Hard
f(x) = sin x is approximated by its Maclaurin polynomial of degree 2 at x = −0.5. Use the Lagrange error bound M·|x|ⁿ⁺¹/(n + 1)! with M = 1 to find the largest possible error |R₂|.
f(x) = sin xn = 2x = −0.5M = 1
|R₂| =
6.Hard
Find the coefficient c₃ of (x − 2)³ in the Taylor series of f(x) = e2x about a = 2.
f(x) = e2xa = 2k = 3
c₃ =
Answer key
- 1. n = 18
- 2. S7 = 19.84
- 3. L = 2
- 4. x = 1.25
- 5. |R₂| = 0.02083
- 6. c₃ = 72.8
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