Question

How do you write an equation that contains points (5, 1) and is perpendicular to y=3?

Answer 1

`x=5`

Explanation:

`y=3` is a horizontal line
Any line perpendicular to it must be a vertical line (that is it must be of the form `x=c` for some constant `c`)

If such a line goes through `(5,1)` it must be
`color(white)("XXX")x=5`