Question

The equation of the line perpendicular to the y-axis that passes through the point (–5, 1) is y = 1. True or false.

Answer 1

That's true.

If the line is perpendicular to the y-axis, then it's horizontal,
and parallel to the x-axis.

Every point on the line has the same y-coordinate. If the point (-5, 1)
is on the line, then all the points (any number, 1) are also on it.
The equation of the line is
[ y = 1 ] .