Question

Select the equation which graphs to a vertical line at -3.
A) y=-3
B) x=-3
C) y=-3x
D) x=-3y

Answer 1

Answer: B) x = -3

Every point on this line has one thing in common: the x coordinate is -3. This is why x is fixed at -3, so we simply say the equation is x = -3

Some example points on this line are (-3,10) and (-3,2)

The y coordinate can be anything you want, so that is why it doesn't show up at all (because it doesn't affect how x will turn out).