What is the slope m of a line that is perpendicular to the line represented by x = 6? (If an answer is undefined, enter UNDEFINED.)

Answer 1

A line of the form x = c, where c is a constant is a vertical line and has an undefined slope
A line of the form y = k, where k is a constant has a slope of 0.

Lines that are perpendicular have slopes that are negative reciprocals of each other.

So .....

Answer 2

it is undefined??

Answer 3

No, as I said the given line has undefined slope, so a perpendicular
line would have a slope of 0.