Chapter 3: Functions of Several Variables
Section 3.3: Quadric Surfaces
Example 3.3.4
Put the equation into standard form for a quadric surface, identify the surface, draw its graph, and discuss the nature of the level curves and plane sections.
Solution
Mathematical Solution
Figures 3.3.4(a, b) contain a graph of the surface defined by the given equation,
whose standard form is
obtained by completing the square in . The standard form is the equation of a parabolic cylinder.
The point would be the vertex of the parabola in the -plane.
The level curves, drawn on the surface of the cylinder, are parabolas.
The cross sections are vertical lines in the -plane.
The cross sections are pairs of vertical lines in the -plane.
= =
Figure 3.3.4(a) Parabolic cylinder with cross sections
Figure 3.3.4(b) Parabolic cylinder with cross sections
Maple Solution - Interactive
Obtain the standard form
Control-drag the given equation. Press the Enter key.
Context Panel: Complete Square≻
Select and use the Smart Pop-Up to subtract this from both sides.
Unfortunately, Maple 2020 is unable to draw the required graph interactively.
Maple Solution - Coded
Define so that the graph of is a quadric surface
Complete the square and put into standard form
Obtain the equivalent the surface in Figures 3.3.4(a, b)
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