We don´t need to determine the real zero of this function, but just to determine between which consecutive integers the real zero is located. If we assume that x=0: f(0)= 3*0-10*0+22*0-4 = -4 and for: x=1: f(1)=3*1-10*1+22*1-4=3-10+22-4=11 It means that the real zero is between 0 and 1.