Series and Convergence flashcards

22 practice cards drawn from the Series and Convergence lessons. Tap a card to turn it over. Every answer is checked against the lesson it came from.

Read the Series and Convergence lessons in full →

Σ(r² + 2r) splits into

Σr² + 2Σr

from “Sums of Squares and Cubes”

Σr³ for r = 1 to 3 equals

36

from “Sums of Squares and Cubes”

As n grows without bound, Σ 1/(r(r + 1)) tends to

1

from “The Method of Differences”

1/(1·2) + 1/(2·3) + 1/(3·4) equals

3/4

from “The Method of Differences”

Terms shrinking to zero proves

nothing on its own

from “The nth Term Test for Divergence”

What does the nth term test say about Σ n/(2n + 1)?

it diverges

from “The nth Term Test for Divergence”

Σ 1/nᵖ converges exactly when

p > 1

from “The p-Series”

Does Σ 1/√n converge or diverge?

diverges

from “The p-Series”

Σ (2n + 1)/(n³ + 5) is best compared with

Σ 1/n²

from “Comparison Tests for Series”

aₙ/bₙ → 3 and Σbₙ diverges, so Σaₙ

diverges

from “Comparison Tests for Series”

The alternating series test needs the sizes to

fall to zero

from “The Alternating Series Test”

The series 1 − 1/2 + 1/3 − 1/4 + … is

conditionally convergent

from “The Alternating Series Test”

By the ratio test, Σ 2ⁿ/n!

converges

from “The Ratio Test”

When L = 1, the ratio test

decides nothing

from “The Ratio Test”

The radius of convergence of Σ xⁿ/n is

1

from “Radius and Interval of Convergence”

The radius of convergence of Σ xⁿ/n! is

from “Radius and Interval of Convergence”

The Maclaurin series of ln(1 + x) begins

x − x²/2

from “The Standard Maclaurin Series”

1/(1 − x) expands as

1 + x + x² + …

from “The Standard Maclaurin Series”

The Taylor series of ln x about a = 1 begins

(x − 1)

from “Taylor Series About a Point”

Term n of a Taylor series about a is

f⁽ⁿ⁾(a)(x − a)ⁿ/n!

from “Taylor Series About a Point”

Approximating sin x by its degree-3 polynomial on |x| ≤ 1, the error is at most

1/24

from “The Lagrange Error Bound”

In the Lagrange bound, M stands for

an upper bound for the next derivative

from “The Lagrange Error Bound”

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