## Algebra and Trigonometry 10th Edition

F = $\frac{gk}{r^{2}}$
If variables vary directly then y = x, so as one increases the other increases. If variables vary inversely then y = $\frac{1}{x}$, so as one increases the other decreases. In this example, F = $\frac{gk}{r^{2}}$ where k is a constant.