The slope is also known as the rate of change. The slope of a graph is the rate at which it changes.
It is important to remember that the slope of a graph can be a positive or negative number (including fractions). The next example shows a decreasing graph, which always has a negative slope.
Worked example 2 Jodie has a tin with 32 sweets in it. She eats four sweets a day. (i) Create a table to show how many sweets will remain in the tin after fi ve days. (ii) Draw a graph to show how the number of sweets decrease each day. (iii) Find the slope of this graph.
Solution (i)
(iii)
20 22 24 26 28 30 32 34
A decreasing, or negative, slope can be thought of as fall