We know that f of two, oh, sorry, we know that f of four is. We know that f of four is the square root of four, which is going to be equal to two, or the principal root of four, which is equal to positive two. And what we want to approximate, we want to figure out what f of, we want to figure out what f of 4.36 is equal to. This is just another way of framing the exact same question that we started off this video. So let's just imagine our function. Let's just imagine it for a second. So let me draw some axes.