Question

What is the slope perpendicular to the line y=10?

Answer 1

See the entire solution explanation below:

Explanation:

Because there is no `x` term in this equation this is, by definition, a horizontal line where for any and all values of `x`, `y` is `10`. And, by definition a horizontal line has slope `0`.

A line perpendicular to a horizontal line is a vertical line. A vertical line, by definition has a slope which is undefined.

Therefore the slope of any line perpendicular to `y = 10` is undefined.