Well, I only got a few knowledge about that, so here it is:
1. Square the first term of the binomial to get the first term of the product
2. Multiply the first term to tha second term then multiply it by two. This gives us the middle term of the product.
3. Square the second term to get the last term of the answer.
4. The sign of the middle term follows the sign of the given binomial.
5. The product of the square of binomial is called a PERFECT SQUARE TRINOMIAL