##### Math Terms

constant of proportionality

the constant ratio in a proportional linear relationship

constant of variation

a constant ratio in a direct variation

constant rate of change

the rate of change between any two points in a linear relationship is the same or constant

direct variation

a relationship between two variable quantities with a constant ratio

linear relationships

a relationship that has a straight line graph

point - slope form

an equation of the form y - y1 = m(x-x1), where m is the slope and (x1,y1) is a given point on a non-vertical line

rise

the verticle change between any two points on line

run

the horizontal change between any two points on a line

slope

the rate of change between any two points on a line. The ratio of the rise, or vertical change, to the run, or horizontal change

slope - intercept form

an equation written in the form y = mx + b, where m is the slope and b is the y - intercept

standard form

an equation written in the form Ax + By = C

substitution

an algebraic model that can be used to find the exact solution of a system of equations

systems of equations

a set of two or more equations with the same variables

x - intercept

the x - coordinate of the point where the line crosses the x - axis

y - intercept

the vertical number line that helps to form the coordinate plane