Graph Each inequality?

Question

These are hyperbolas
a. xy greater than or equal to 8
b. xy greater than or equal to 1
c. xy greater than or equal to 0

b. xy less than or equal to -1

I know how to graph all of them except the 1's all i dont know how to do is shade can someone please explain to me where to shade and why

Answer 1

Check these graphs, they are the general shape
and shading. To know where to shade, substitute ordered pairs from the regions separated by the graph to see if they
satisfy the inequality.
For instance, the region containing (10,10) should be
shaded in the graph of xy ≥ 8, because 10*10 ≥ 8


http://img187.imageshack.us/img187/6727/xyvn2.png

Answer 2

y >= 8/x
Look at the part of the graph in the 3rd quadrant. Pick a point below the graph such as (-4,-4). Plug thes values in and see if the inequality holds. You get -4 >= 8/-4 which is untrue. So you want to shade above the curve

Now do the same with the part of the graph in the 1st quadrant. Pick a poin above the curve such as (5,5)
Then 5 >= 8/5. This is tru so shade above the curve.

Use same logic for other two problems.