[Home][General][Business][Engineering][VCE][Learning Units][Tool Box][Glossary] Graphs Basic Terms
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Graphs Units       Graphs show us how two or more quantities are connected to each other.Before we discuss the graphs, it is important to go through some basic terms.

 x and y axis Ordered Pair Relations Domain Range Rule of Equation x and y intercepts gradient Finding the gradient of line AB

X -axis  Horizontal line

Y - axis Vertical line

Origin - The origin is the intersection of the x and y axes

Let's look at this diagram. Ordered pair - Any two numbers where the order is important
For example, (2,3) is an ordered pair. It gives the location of the point.
The point A is located 2 units in the x-direction and 3 units in the y-direction.
The point B is located 1 unit in the negative x-direction and 2 units in the negative y-direction.
In other words, in an ordered pair, the first number gives the number of units along the x-axis and the second number gives the number of units along the y-axis.

Relation - A relation is a set of ordered pairs, can be set out in a table or can be listed as a set of ordered pairs.

For example:
This is a relation  set out as a set of ordered pairs.
{(1,5)  (2,10)  (3,15)  (4,20)  (5,25)} is a relation.

The same relation can be set out in a table.(as below)

 x 1 2 3 4 5 y 5 10 15 20 25

The domain of the relation is {1, 2, 3, 4, 5},which are the first-named numbers.

The range of the relation is {5, 10, 15, 20, 25}, which are the second-named numbers.

The rule or equation is how the numbers are related to each other.
In the above relation, we can write the rule as, y = 5 × x or   y = 5x.
This is a linear relationship.

x-intercepts are where the graph cuts the x axis.

y-intercepts are where the graph cuts the y axis. The gradient is the slope of a straight line.  Find the gradient of line AB The gradient of line AB is the slope of the line, which is equal to the ratio between the
vertical distance(rise)  and the horizontal distance(run). Vertical distance =  5units,              Horizontal distance = 3units
rise   =  5units,                                     run   =  3units  [Home][General][Business][Engineering][VCE][Learning Units][Tool Box][Glossary]