A polynomial is said to be binomial if it has only two terms. There are a lot of algebraic identity for binomials. (x-y)^2 is the square identity of the binomial subtraction. It is not that easy to solve this identity with x and y having complex values. Hence, this chart provides you with the simplified values of the square of the binomial subtraction [(x-y)^2] for different x and y values.
(x - y)2 = x2 - 2xy + y2