So first let's see where our first derivative is equal to 0 and get our critical points, or at least maybe, also maybe where it's undefined. So this is equal to 0, if we want to set, the only place that this can equal to 0 is if this numerator is equal to 0. This denominator actually, if we are assuming we're dealing with real numbers, this term right here is always going to be greater than or equal to 0 for any value of x, because it's an even exponent, so this thing can never equal 0, right, because you're adding 27 to something that's non-negative, so this will never equal 0, so this will also never be undefined. So there's no undefined critical points here, but we can set the numerator equal to 0 pretty easily. If we wanted to set this equal to 0, we just say 4x to the third is equal to 0, and we know what x value will make that equal to 0, x has to be equal to 0. 4 times something to the third is equal to 0, that something has to be 0. x to the third has to be 0, x has to be 0. So we can write f prime of 0 is equal to 0.