Question

Which of the following expressions are undefined

Answer 1

A rational expression is undefined for ANY value of the variable that makes the denominator equal to 0. So I say that the domain for rational expression is all real numbers except those that make the denominator equal to 0.

Answer 2

All of them because whenever you have a zero in the denominator it becomes undefined, because you can't divide a number by zero like zero can't go into seven. Hope this helps!