## Calculus: Early Transcendentals (2nd Edition)

The net area measures the total area bounded by the graph of the function and $x$ axis between some boundaries for $x$ but the parts of the area above the $x$ axis with the plus sign and the area under the $x$ axis with the minus sign.
To find the net area we add the areas of the pieces bounded by the graph of the function and $x$ axis and we subtract areas of those pieces that are below $x$ axis.