Real Analysis
Lesson 1 of 3 10 min +90 XP

Sequences & Convergence

When does a sequence approach a limit?

What you'll learn

  • Define convergence informally
  • Recognize a bounded sequence
  • Read epsilon notation
Zooming in on a photo

Zoom into a digital photo and each doubling reveals a little less new detail until the image settles and stops changing. A convergent sequence behaves the same way: its terms crowd in around one limit value and stay there.

Getting arbitrarily close

A sequence (aₙ) converges to L if its terms get and stay arbitrarily close to L. Formally: for every ε > 0 there is an N such that |aₙ − L| < ε for all n > N.

Bounded vs convergent

Every convergent sequence is bounded, but not every bounded sequence converges (e.g. (−1)ⁿ oscillates).

Knowledge Check

+25 XP / correct

1. The sequence aₙ = 1/n converges to…

2. The sequence (−1)ⁿ is…