Or maybe they actually are defined there, but it's removable discontinuity. So all of these are examples of discontinuous functions. Now if you want the more mathy understanding of that, and we've looked at this before, we say that a function, f, is continuous at some value x equals a if and only if, draw my little two-way arrows here, say if and only if the limit of f of x as x approaches a is equal to the value of the function at a. So once again, in order to be continuous there, you at least have to be defined there. Now when you look at these, the one thing that jumps out at me, in order to be continuous for all real numbers, you have to be defined for all real numbers, and g of x is not defined for all real numbers. It's not defined for negative values of x. And so we would rule this one out.