Rational Number
A rational number is a
number that can be written as a
fraction with
integers
as the
numerator and
denominator.
This includes fractions,
regular counting numbers,
negative numbers,
terminating decimals and
repeating decimals.
 |
|
 |
|
Rationalize the
Denominator
Rationalizing the
denominator is a process that gets rid of the
radical in the denominator.
Examples:
To learn how to rationalize the denominator, check out my
Rationalizing Denominators lesson. |
|
|
|
Ray
A
ray is a
partial line that
starts at one point and
goes on forever and ever in one direction. |
 |
|
|
|
Real Numbers
The set of Real
Numbers consists of both the
rational and
irrational numbers. |
|
|
Reciprocal of a Number
The reciprocal of a
number is
the number you need to multiply
by to get 1 as the answer.
The numbers below are reciprocals of each other.
 |
|
|
|
|
|
|
Rectangular
Coordinate System
The rectangular
coordinate system is
a plane (meaning that it's flat) made up of an
x axis (the horizontal
line) and a y axis
(the vertical line).
Coordinates on the
rectangular coordinate system are a set of
numbers officially called "an
ordered pair" that
are in the form (
x
, y
) ... The x guy is how far to the right or left you've
counted over... and
the y guy is how far up or down you've counted.
For more info on graphing
with rectangular coordinates, check out my
Plotting Points lesson. |
 |
|
|
|
Regular Polygon
Regular polygons are
polygons whose sides are the same length and whose angles
are the same size. Below is a
regular
triangle (which is called an
equilateral triangle), a
regular
quadrilateral (which is
a
square), a
regular
pentagon, a
regular
hexagon and a
regular
heptagon.
 |
|
|
Relation
A relation is an
ordered pair
in the form:
(x,
y)
Example: (2,
-3)
Ordered pairs are used as
rectangular
coordinates. |
|
|
Relatively Prime
Two numbers are
relatively prime if they have
no common
factors other than the number
1. Another way
to define it is to say that two numbers are relatively prime
if their
greatest common divisor is
1.
Examples: 9 and
14 are relatively prime since
their greatest common divisor is 1...
4 and 18
are NOT relatively prime since their greatest common divisor
is 2.
|
|
|
Remainder
The
remainder is what might be
"left over" when you are doing a division problem. For
example, 3
goes into
17 five times with
2 left over... So, the
remainder is 2. We write
this as
 |
|
|
Repeating Decimal
A repeating decimal is
a
decimal where the decimal part repeats. This
means that one or more numbers just keep
showing up over and over again. We put a
bar over the repeating part:
Repeating decimals can always be converted into
fractions. Repeating decimals are a
rational numbers. |
|
|
|
|
|
|
Right Angle
A
right angle is an angle
whose measure is 90 degrees.
The symbol always used to show
that an angle really IS a right angle, is a
little square in the corner.
In a geometry problems, if the angle LOOKS like it's
90 degrees, but there is no "square
symbol," then, it's NOT really 90 degrees!
This is a very common trick among geometry teachers
and people who make those "standardized" tests!
So... beware. |
 |
|
|
|
|
|
|
|
Root of a Polynomial
The roots of a
polynomials are the solutions when the polynomial is set
equal to zero. This is a bit too complicated for a
short definition, so check out my
Zeros of a Polynomials lesson. |
