What is the missing term from the last term of the trinomial x² + 5xy + 4 so that it is factorable as the product of binomials?

The correct answer is: y²

x² + 5xy + 4y²
Factors of 4 are 4 and 1.
4 + 1 = 5
(x + 4y) (x + y) = x² + xy + 4xy + 4y² = x² + 5xy + 4y²

In mathematics, factorization or factoring consists of writing a number or another mathematical object as a product of several factors, usually smaller or simpler objects of the same kind.