Question

(Medal&Fan)

Answer 1

I think it is the first one because you can't do 1/0, it's not possible. And when you get a 0 for the denominator, you always say it's undefined. I don't know how to explain it exactly, but just remember that you cannot divide any number by 0

Answer 2

The other ones all say must, but they dont really have to be a must, its more sometimes

Answer 3

that's what i got too!

Answer 4

cool :)