Zeroes of Functions

A zero of a function f is a number c for which f(c)=0. A zero c of a function f can be a real or a complex number. A complex number is a number of the form z=a+bi, where I squared equals -1 and a and b are real numbers. The number a is called the real part of z and b which is called the imaginary part of z. The symbol I is called the imaginary unit and it is common practice to write it as I=square root of -1. If z=a+bi is a complex number, then z=a-bi is called its conjugate. Thus the simple polynomial function f(x)=x squared plus 1 equals zero are plus/minus square root of negative one, that is , I and -I. 

Here is a picture of a problem that involves zereos of a function!