1. The quantity b² - 4ac, where a,b,c are coefficients of a given quadratic polynomial: ax² + bx + c.

2. More generally, for the polynomial equation a₀xⁿ + a₁x^n-1 +...+a_nx₀ = 0, a₀^2n-2 times the product of the squares of all the differences of the roots of the equation, taken in pairs.