Question

Which equation is perpendicular to the y axis

A) x=-2

B) x=1/2 y

C) y=-6

D) y=x

Answer 1

C is the only one that is perpendicular.
The quickest way I can explain it is that the y-axis runs up and down, making the slope undefined. Something perpendicular to an undefined slope is a 0-slope. The only equation of the choices that has a 0-slope is C. Comment if you want a more detailed answer.