Multivariable Calculus — Vectors & Gradients
Finding a minimum
continues from lesson 3 — values defined earlier in the course stay live here
ELI5: a low point of a landscape is flat in every direction — all partial derivatives are zero. The bowl f(x, y) = x² + y² bottoms out at the origin (0, 0), where its height is 0 and nowhere nearby is lower.
✓ pass the origin really is the bottom of the bowl
Where next: Proofs & Logic — the rules of reasoning that make every theorem above certain, not just plausible.