Exercise · ZW-LEVEL-CURVE-004 · ★★☆ Intermediate
What is the level curve \(f(x,y)=0\) of \(f(x,y)=xy\)?
Choose one option.
Show answer
- B. The union of the \(x\)- and \(y\)-axes
Explanation
\(xy=0\) requires \(x=0\) or \(y=0\), that is, both axes. For \(c\neq 0\) it would be a hyperbola.
Review the concept: Level curve
A level curve of a function \(f\) of two variables is the set of points in the plane where \(f\) takes one same constant value \(c\).
\[f(x,y)=c\]
More practice problems: level curve
- ZW-LEVEL-CURVE-001 For f(x,y)=x^2+y^2, what is the level curve f(x,y)=4?
- ZW-LEVEL-CURVE-002 The level curve f(x,y)=3 of f(x,y)=2x-y is the line:
- ZW-LEVEL-CURVE-003 Which point lies on the level curve f(x,y)=1 of f(x,y)=x^2-y?
- ZW-LEVEL-CURVE-005 For f(x,y)=x^2+y^2, for which values of c is the level curve f(x,y)=c empty?
- ZW-LEVEL-CURVE-006 Can two different level curves of the same function f intersect?
- ZW-LEVEL-CURVE-007 The level curve f(x,y)=4 of f(x,y)=x^2+4y^2 meets the x-axis at:
- ZW-LEVEL-CURVE-008 For f(x,y)=x^2+y^2, how many times larger is the radius of the level curve f=9 than that of f=1?
- ZW-LEVEL-CURVE-009 For f(x,y)=(y)/(x), the level curve f(x,y)=2 is: