But the enzyme basically converts that substrate into the product relatively slowly. And so at least initially at the beginning, we don't actually form a lot of the product. So at a time of t approximately equal to zero, what that means is because we don't have a lot of product form, this reaction will take place at a very very low rate. And so by approximating that we can essentially remove this entire equation and remove the k minus two term and that's because this reaction takes place at a negligible rate. So once again to simplify this equation here we can instead study the reaction at the beginning, that is when the time is approximately equal to zero, right at the beginning of that reaction. At that point in time, the rate V is equal to V Naught.