Since there isn't a line under the < sign, this means that we used a dotted or dashed line. The dotted or dashed line indicates that we do NOT include the boundary as part of the solution set.
Since y is isolated and we have a less than sign, this means we shade below the dashed/dotted boundary line. Specifically, the boundary line is the graph of y = 2x+1. This boundary line goes through (0,1) and (1,3). Again, points on this boundary line are NOT part of the solution set.
So in summary we have: A dashed or dotted boundary line The shaded region is below the dashed/dotted boundary line.
