NapkinCalc

Calculus 2B — Series & Taylor

Part 2 of 2. Geometric series that converge, the harmonic series that doesn't, and Taylor polynomials impersonating functions.

Part 2 of 2. Can you add infinitely many numbers and get a finite answer? Sometimes yes, sometimes no — and the difference powers everything from loan math to how your calculator computes sine.

  1. 01 Geometric series — infinite sums with finite answers ELI5: add 1 + ½ + ¼ + ⅛ + ⋯ forever and you do not get infinity — each term covers half the remaining gap to 2. Any geometric series (each term a fixed ratio r…
  2. 02 When it does NOT converge ELI5: shrinking terms are not enough. The harmonic series 1 + ½ + ⅓ + ¼ + ⋯ has terms heading to zero, yet its total grows without bound — just agonizingly…
  3. 03 Taylor series — polynomials impersonating functions ELI5: near a point, any smooth function can be mimicked by a polynomial built from its derivatives. The first two terms of sin(x) are x − x³/6; it hugs the…

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