Which is NOT a function?

A. y - x = 6
B. y = 2x
C. x = -2
D. y + x =12

Please help. God bless you!!

3 answers

all the choices are straight lines.

The only line which is NOT a function is a vertical line.
Which line is vertical ?
the x = -2 is a vertical line, or undefined slope... so that is the answer right?
Of course, you and I both said that.