Multivariable Calculus

How to solve

The equation f(x, y) = c for f = x² + y² is the circle of radius √c centered at the origin.

Steps

  1. If you know c, radius is √c.
  2. If you see radius r, then c = r².

Example

x² + y² = 4

  1. r = 2.
  2. Level value c = 4.

Answer: 2 or 4 depending on the prompt

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