Question

Match the function with the description of its level sets (the sets z=constant).


A. a collection of circles centered at the origin.
B. a collection of ellipses.
C. a collection of parallel lines.
D. a collection of parabolas.
E. a collection of hyperbolas.
??? 1. z = √{1+x} +y
??? 2. z = (x+y−1)−1
??? 3. z = 5x−3y
??? 4. z = x2−2xy+y2+x+y
??? 5. xy+z2 = 1
??? 6. z = √{15−x2−y2}
??? 7. z = (x2+2y2)−2