Use the graph to determine whether y varies directly as some power of x or inversely as some power of x. Explain.
1.

2.

Determine whether the variation model represented by the ordered pairs (x, y) is of the form y = kx or y = k / x, and find k. Then write a model that relates y and x.
3. (5, 1), (10, 1/2), (15, 1/3), (20, 1/4), (25, 1/5)
4. (5, 2), (10, 4), (15,6), (20,8), (25,10)
5. (5, ˆ’3.5), (10, ˆ’7), (15, ˆ’10.5), (20, ˆ’14), (25, ˆ’17.5)

4, 4) 2 4 6 8 2.