In the study of ecosystems, predator-prey models are often used to study the interaction between species. Consider populations of tundra wolves, given by , and caribou, given by , in northern Canada. The interaction has been modeled by the equations
.

(a) What values of and correspond to stable populations?
(b) Suppose . After finding population pairs that lead to stable populations, is it possible for the species to live in balance or both species become extinct? Answer "b" for balance and "e" for extinction.