Limit

Limit is a important point in Mathematics and calculus， it can tell us mow big or small can be and we also can know range and domain. the point of limit can show us how to apply and how special the point is. For example, in economic. If well sell some something, we want to know how much profit we can gain. We need creat a model first, then we can know the point of limit, and we can estimat that how much profit we can get. So, limit is important in practical application and calculus.