3D lab · Limits

Limits of Two-Variable Functions on 3D Surfaces

Explore 3D surfaces and approach the origin along lines and parabolas to see when a limit exists and when it fails.

Last updated: 26 October 2026

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Explore 3D surfaces and approach the origin along lines and parabolas to see when a limit exists and when it fails.

Walk toward the origin along different paths (pink). If two paths end at different heights, the limit does not exist.

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Limits of Two-Variable Functions on 3D Surfaces

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What's happening? Walk toward the origin along different paths (pink). If two paths end at different heights, the limit does not exist.
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FAQs

Frequently asked questions

How can you prove a two-variable limit does not exist?

Find two paths that give different limiting values.

Does xy/(x² + y²) have a limit at the origin?

No. Along y = mx it equals m/(1 + m²), which depends on m.

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