So let's see, if we factor in e to the negative 2x squared, I'll do that in green, we're going to have, this is equal to e to the negative 2x squared times, we have here 1 minus 4x squared. So this is the derivative of f. Now, where would this be undefined or equal to 0? Well, let's see, e to the negative 2x squared, this is going to be defined for any value of x. This part is going to be defined, and this part is also going to be defined for any value of x. So there's no point where this is undefined, but let's think about when this is going to be equal to 0. So you have this product of these two expressions equaling 0. e to the negative 2x squared, that'll never be equal to 0. If you get this exponent to be a really, I guess you could say very negative number, you will approach 0, but you'll never get it to be, you'll never get it to be 0.