And now let's see how we can simplify this a little bit. Both of these terms are divisible by x to the fourth and they're both divisible by three. So let's factor out a three x to the fourth times, you factor out a three x to the fourth here, you're left with a two x. And then over here you have minus five has to be less than zero. Any interval where this is true, we are going to be decreasing. Now, how do we get this to be less than zero? Well, if I take the product of two things and it's less than zero, that means that they have to have different signs, either one's positive and the other is negative or one's negative and the other's positive.