* *

**Solve joint variation problems**

** **

It is possible for one variable to depend on several others. If one variable varies directly as the

*product *of several other variables (perhaps raised to powers), the first variable is said to *vary jointly *as the others.

**Joint Variation**

*y *varies jointly as *x *and *z *if there exists a real number *k *such that

*y * = *kxz.*