Question

(x-1)(x-2) = 0 represents, in three dimensional space, a:

• A. Pair of straight lines
• B. sphere
• C. Pair of parallel planes
• D. an empty set

Answer 1

Answer: (C)

Pair of parallel planes

Answer 2

The equation $(x-1)(x-2)=0$ in 3D space implies $x=1$ or $x=2$. Each of these is an equation of a plane parallel to the yz-plane.