The expression "y²" represents the square of a variable "y." In mathematics, squaring a number means multiplying it by itself. For example, if y equals 3, then y² equals 3 × 3, which is 9. This concept is fundamental in algebra and is often used in equations and functions. In geometry, y² can appear in the equation of a circle or a parabola. For instance, the equation of a circle centered at the origin is x² + y² = r², where r is the radius. Understanding y² helps in solving various mathematical problems and analyzing shapes in coordinate systems.