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.
... equation
<math>ax^2+bx+c=0</math>
in terms of the coefficients a, b and c, which are assumed to be real (but see below for generalizations) with a ...