b2<4ac means that the discriminant is less than 0 . Therefore, f(x)>0 for all x if the coefficient of x2 is positive, and f(x)<0 for all x if the coefficient of x2 is negative. We are given that f(m)<0 and m is an integer. So the set containing values of m will either be empty if the coefficient of x2 is positive, or it will be a set of all integers if the coefficient of x2 is negative.