For an algebraic number field K, a quantity of this name determines which primes ramify K and equals the determinant of a trace pairing matrix. For a polynomial, this noun denotes the product of all squared differences between pairs of roots. This noun appears in the name of a supervised learning method that finds weighted sums of features that maximize the ratio of between and within-class variances; that linear method was developed by Fisher. A complicated (-5[1])quantity of this name that includes the term “27 a-squared d-squared” appears in the innermost square root in Cardano’s formula. The sign of a quantity of this name determines the number of roots of a quadratic polynomial. For 10 points, what noun denotes the quantity “b-squared minus (-5[1])4 (-5[1])a c” (10[2]-5[1])in the quadratic formula? ■END■ (10[2]0[7])