Question 43559
x-2y greater or equal to 4
x-2y>=4
Solve for y, as follows:
y<=(1/2)x+2
Graph the equality y=(1/2)x+2
using points (0,2),(-4,0)
Shade the area "above" the line to graph y>(1/2)x+2

x greater or equal to 4
x>=4
Graph the equality line: x=4 using points (4,0) and (4,2)
Shade the area "to the right" of the line to graph x>4

Cheers,
Stan H.