Data Table 
A list of
x
values and their corresponding
y
values.
Negative Slope 
y
always decreases when
x
increases and
y
always increases when
x
decreases.
Ordered Pair 
A pair of numbers in a specific order. For example,
(3, 7)
and
(8,  1)
are ordered pairs. Two ordered pairs are equivalent if their first members are equal and their second members are equal. However, the order of the two numbers is important;
(1, 2)
is not equivalent to
(2, 1)
.
Origin 
The point
(0, 0)
.
Parallel Lines 
Two lines are parallel if they have the same slope. Parallel lines, when extended, do not intersect at any point.
Perpendicular Lines 
Two lines are perpendicular if their slopes are opposite reciprocals of each other. Perpendicular lines intersect each other at right angles.
Positive Slope 
y
always increases when
x
increases, and
y
always decreases when
x
decreases.
Slope 
Given two points
(x
_{1}, y
_{1})
and
(x
_{2}, y
_{2})
on a line, the slope of the line is equal to:
m =


xaxis 
The horizontal axis of a graph, with which the
x
values are plotted.
xcoordinate 
The number which corresponds to the value of
x
in an ordered pair.
xintercept 
The point at which the graph of a line crosses the
x
axis. The point at which
y = 0
.
xygraph 
A twodimensional way of representing points.
x
values are plotted with the horizontal axis, and
y
values are plotted with the vertical axis.
xygraph
xygraph
yaxis 
The vertical axis of a graph, with which the
y
values are plotted.
ycoordinate 
The number which corresponds to the value of
y
in an ordered pair.
yintercept 
The point at which the graph of a line crosses the
y
axis. The point at which
x = 0
.