Joe Grow, an avid indoor gardener, has found that the number of happy plants, h, depends on the amount of light, l, and water, w. In fact, Joe noticed that plants require twice as much water as light, and any more or less is wasted.

What is his production function?

Suppose Joe is using 1 unit of light, what is the least amount of water he can use and still produce a happy plant?

If each unit of light costs w₁ and each unit of water costs w₂, what is Joe's cost function c(w₁,w₂,h) ?