# Applications of Function Models

## Word problems using function models

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Practice Applications of Function Models

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Oh Deer!

Credit: Dawn Huczek
Source: http://www.flickr.com/photos/31064702@N05/3271066657

When does a cute woodland creature become a menace to the environment? When conservation efforts are too successful. A hundred years ago, the white-tailed deer was nearly extinct in North America. Today, deer pose a more immediate threat to native plants and animals in the United States than climate change. How did members of a harmless species of herbivore become so dangerous? It has to do with their exponential growth curve.

#### Lots of Habitat and No Predators

White-tailed deer were once abundant in the Eastern United States. Then, deforestation and overhunting took their toll. By the 1920s, the deer were almost driven to extinction. Conservationists and hunters then formed a partnership to save this graceful forest creature. They began by limiting the number of deer that could be killed each year and by creating game preserves, where deer were protected. They hoped to return the deer population to sustainable levels.

Their hopes were wildly exceeded. Today, an exponential function is the best model for deer population growth, and populations continue to swell out of control. How did this happen? Throughout most of the U.S., deer have no predators except for humans. In addition, much of the country has been reforested, as we no longer need wood for fuel and agriculture has become more efficient. The current mix of forests, fields, and suburbs has proven to be the perfect environment for deer.

Credit: Don DeBold
Source: http://www.flickr.com/photos/ddebold/2791271947/

Their growing populations are causing huge problems. Every year, vehicle collisions with deer result in 200 human deaths and billions of dollars spent on property damage and preventive measures. Farmers and gardeners lose crops as deer eat everything they plant. Even worse, deer are actually contributing to the destruction of American forests. Their large numbers mean that they overgraze. They eat young trees and native plants, allowing invasive species to flourish, and they decimate the underbrush that other animals need to survive. Some states have encouraged hunters to take more deer, but ecologists say that these measures aren’t strong enough. We need to find more ways to bring deer populations back under control.

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