Each state of the United States selects two senators to represent their states in the United States Senate. In 1913, the 17th Amendment[?] to the United States Constitution provided for the direct popular election of senators; prior to this, senators were selected by state legislatures.
... b2 – 4ac is called the discriminant of the quadratic equation, because it discriminates between three qualitatively different cases:
If the discriminant is zero, ...