Question

What does the set of points whose $y$-coordinate is 0 represent?

• A. $x$ axis; $y=0$
• B. $y$ axis; $x=0$
• C. $x$ axis; $x=0$
• D. $y$ axis; $y=0$

Answer 1

The correct option is A $x$ axis; $y=0$

The set of points whose $y$-coordinate is $0$ can be represented as $(x,0)$, where the values of $x$ can be anything.

This means the points with $y$-coordinate as $0$ lie in such a line which in NOT above or below the $x$-axis. This only happens when that line coincide with the $x$-axis, i.e., $y=0$.