The expression "n(3n - 1)" represents a mathematical formula where "n" is a variable. This formula can be expanded to show that it is a quadratic expression, specifically 3n² - n. It is often used in algebra to explore relationships between numbers and can be applied in various mathematical problems. In combinatorics, this expression can help calculate certain types of arrangements or selections. For example, it may relate to the number of ways to organize items or the number of paths in a graph. Understanding such expressions is essential in fields like mathematics and computer science.