##### 8th grade math vocab

constant of proportionality

The **constant** ratio between two quantities is also
called as **constant of proportionality** i.e. if x is
proportional (directly) to y, then k = . There are times when you will
need to find the **constant** in an equation.

constant of variation

The constant of variation in a **direct variation** is
the constant (unchanged) ratio of two variable quantities. Example 1:
If y varies directly as x and y = 15 when x = 24, find x when y = 25.
The constant of variation in an indirect variation is the constant
(unchanged) product between two variable quantities.

constant rate of change

For straight lines, the **rate of change** (slope) is
**constant** (always the same). For every one unit that
is moved on the x-axis, two units are moved on the y-axis. This is
true at any location on the line.

direct variation

1 : mathematical relationship between two variables that can be
expressed by an equation in which one variable is equal to a constant
times the other. 2 : an equation or function expressing **direct variation**

linear relationships

**Linear relationships** can be expressed in a graphical
format where the variable and the constant are connected via a
straight line or in a mathematical format where the independent
variable is multiplied by the slope coefficient, added by a constant,
which determines the dependent variable.

point slope form

**Point slope form** is the quickest method for finding
the equation of line given two **points**

rise

A measerment of the movement of the y axis

run

A measurement of the movement of the x axis

slope

In mathematics, the **slope** or gradient of a line is a
number that describes both the direction and the steepness of the
line. **Slope** is often denoted by the letter m. The
direction of a line is either increasing, decreasing, horizontal or
vertical. A line is increasing if it goes up from left to right.

slope intercept form

The **slope**-**intercept form** is simply
the way of writing the equation of a line so that the
**slope**(steepness) and y-**intercept**
(where the line crosses the vertical y-axis) are immediately apparent.
Often, this **form** is called ' y = mx + b'**form**.

standard form

**Standard form** is a way of writing down very large or
very small numbers easily.

substitution

The method of solving "by **substitution**"
works by solving one of the **equations** (you choose
which one) for one of the variables (you choose which one), and then
plugging this back into the other **equation**,
"substituting" for the chosen variable and solving for the other.

systems of eqations

A **system of equations** is a collection of two or more
**equations** with a same set of unknowns. In solving a
**system of equations**, we try to find values for each
of the unknowns that will satisfy every **equation** in
the **system**.

x intercept

where the graph crosses the x axis

y intercept

where the graph crosses the y axis