A function / is continuous at the point a if for any neighborhood V(f(a)) of its value /(a) at a there is a neighborhood U(a) of a whose image under the mapping / is contained in V(f(a)).
A function / is continuous at the point a if for any neighborhoodV(f(a)) of its value /(a) at a there is a neighborhood U(a) of a whoseimage under the mapping / is contained in V(f(a)).