U - Math terms glossary

undefined terms A term used without a specific mathematical definition.

uniform scale   A scale in which numbers that are equally spaced differ by the same amount. When creating a number line or coordinate grid system, you use a uniform scale.

Ex:

union of two sets The set of elements which are in at least one of the sets.

Ex: Let's say you are given the sets A={3,4,5} and B={4,5,6}, the union of the sets A and B, written A U B, would be {3,4,5,6}. Notice that there is no need to list the 4 and 5 twice.

unit cost  The cost per one unit of an object.

unit fraction A fraction with 1 in its numerator and a natural number in its denominator.

Ex: 1/3, 1/7 etc.
Remember ZERO is not a natural number nor is 1/2 or .5 or -7, so no such numbers will be found in the denominator of a unit fraction.

uniquely determined A situation in which there is exactly one element satisfying given conditions.

Ex: In the equation 3x+4=13, x is uniquely determined because only one number satisfies this situation, 3.

unit cube A cube in which every edge has length one unit.

unit square A square in which each side has length one unit.

unknown A variable which can be assigned different values.

unlike terms Terms that involve different variables or the same variable with different exponents.

EX: 3, 3x, and are all unlike terms.

U.S system of measurement A measurement system in common use in the United States today, based on inches and pounds. Also called the customary system of measurement.

12 inches = 1 foot	8 ounces = 1 cup	16 ounces = 1 pound
36 inches = 1 yard	2 cups = 1 pint	2,000 pounds = 1 ton
5,280 feet = 1 mile	2pints = 1 quart
1 square mile = 640 acres	4 quarts = 1 gallon