The distance from the origin to the coordinate x.

Pairs of real number that have the sum 0.

Expressions that are made up of variables, numbers, grouping sym- bols, operation signs, and exponents.

An angle that measures between 0' and 90' formed by a horizontal ray and a ray from the observer to the object observed below.

The sum of the num- bers in a set divided by the number of numbers in the given set.

For each positive inte- ger n, the sequence with the first term a, and nth term a, is an arithmetic sequence if and only if an = a1 + (n - 1)d.

The lines within which the branches of the hyperbola lie, and which are approached by the branches as |x| increases.

A line in the plane of a graph such that the part of the graph on one side of the line is a reflection of the part on the other side.

A polynomial with two terms.

The point in a circle from which the distance to any point on the circle is a constant.