<em>Since a function is based on a set of ordered pairs, where the first element in each pair is from the domain and the second is from the codomain. Also A function is a mapping from a set of inputs (the domain) to a set of possible outputs (the codomain). </em>
<em>The last one doesn't show the correct inputs and outputs</em>
M or the slope has to be constant throughout the graph. This is because in order for a line to be linear it has to be increasing or decreasing at the same rate. So it the slope was 2 from point x 1 -2 then the slope changed to 1 from 3-4 it would not be linear. :)
