# Math Help - Rational Functions?

1. ## Rational Functions?

Suppose p varies directly as the cube of x, and inversely with y. If p=5/8 when x=4 and y=10, find p when x=2 and y=16

How do you set up the steps?

2. When P varies directly with x, it means, $p=k_1x$ for some constant k.

If P varies directly with the cube of x then, $P = k_1 x^3$

When P varies inversely with y it means, $P = \frac{k_2}{y}$

Now if you use the initial conditions provided you should be able to solve for the constants $k_1 \mbox{ and } k_2$

3. ## thanks

Originally Posted by Jen
When P varies directly with x, it means, $p=k_1x$ for some constant k.

If P varies directly with the cube of x then, $P = k_1 x^3$

When P varies inversely with y it means, $P = \frac{k_2}{y}$

Now if you use the initial conditions provided you should be able to solve for the constants $k_1 \mbox{ and } k_2$
Thanks for the quick response, I appreciate it.

4. No Problem.