You could try to plot it instead on MS Excel
You put two heading, knowing on which point the graph passes through:
Code:
x y
0 0
1 1
2 2
3 3
And then, you select the two columns, right-click on graph > Scatter plot
Complete and fill in more details if you want, or remove unnecessary things, then finish. You'll have a graph with the points plotted. Then, you can right click and choose 'Force equation'. You choose from various equation forms and voilą. In my example, you'll see the line y = x being drawn.
Then, you can copy, transport to paint and shade what you need, according to the inequality sign. Save the image, open MS word, and insert the graph.