standard_description: Relate the domain of a function to its graph and, where applicable, to the quantitative relationship it describes.  For example, if the function h(n) gives the number of person-hours it takes to assemble n engines in a factory, then the positive integers would be an appropriate domain for the function.
problem_activity: Samantha found the slope of the line that passed through the points
$${(2, 6)}$$
and
$${(-4, 8)}$$
. Her work is shown below.
$${{8-6\over {2-(-4)}} = {2\over 2+4 }= {2\over 6} = {1\over3}}$$
Samantha made an error in her work. Describe the error and then find the correct slope of the line through the two given points.


aligns: no