Question

Explain how the growth rate function can be decreasing while the population function is increasing.

Short answer

Short Answer Question: Explain how it is possible for a population growth rate to decrease while the population function itself is still increasing. Provide a brief definition of growth rate and population function, and include an example to demonstrate your answer.

Step-by-step solution

1. Definition of terms

(Growth rate is a measure of the change in the size of a population over time. The population function is a mathematical expression that models the size of a population over time.)

2. Understanding growth rate and population functions

(The growth rate function is the derivative of the population function. In other words, it represents the rate of change in the population with respect to time. A positive growth rate means the population is increasing, while a negative growth rate means the population is decreasing. The population function models the overall size of the population at a given point in time.)

3. Decreasing growth rate and increasing population function

(An increasing population function means that the population is growing over time. The growth rate could be decreasing, but it is still positive. In other words, the growth rate is diminishing, or the population is growing at a slower pace, but the overall population is still increasing. This is also expressed as a population function with a positive derivative.)

4. Example

(Consider the population function given as P(t) = 1000(1 + t^2 / (t^2 + 1)). Taking the derivative, we can find the growth rate function. In latex code: \frac{dP}{dt} = 1000( \frac{2t}{t^2 + 1} - \frac{2t^3}{(t^2 + 1)^2}). This growth rate function is positive for all t, but its rate of increase is decreasing. However, the population P(t) is increasing as time t progresses, as seen in the original function. Thus, the growth rate is decreasing, while the population function is increasing.)

Key concepts

Understanding Population Function

The population function is a crucial concept that helps us understand how a population changes over time. It is essentially a mathematical expression or equation, often denoted by something like \( P(t) \), which models the size of a population at any given time \( t \). By plugging in different values of \( t \), we can find out how many individuals are in the population at that specific time.

This function allows us to visualize and predict the population's growth or decline throughout various stages. For example, if we have a population function \( P(t) = 1000(1 + \frac{t^2}{t^2 + 1}) \), it tells us that the population starts at a certain size and then changes as time progresses.

• The function provides a snapshot of the population size at any time point.
• It is a vital tool for analyzing long-term trends and patterns.
• Predicting the future population can help in planning resources and infrastructure.

Grasping the Concept of Derivative

The derivative is a fundamental tool in calculus, used to determine the rate at which a quantity, such as a population, changes with respect to another variable, like time. When applied to a population function, the derivative, denoted \( \frac{dP}{dt} \), represents the growth rate function.

Essentially, the derivative tells you how fast the population is increasing or decreasing at any point in time. In our previous example of \( P(t) = 1000(1 + \frac{t^2}{t^2 + 1}) \), computing the derivative would give us \( \frac{dP}{dt} = 1000( \frac{2t}{t^2 + 1} - \frac{2t^3}{(t^2 + 1)^2}) \), providing insight into the growth speed at different time \( t \).

• The derivative offers a snapshot of population dynamics at any specific moment.
• Positive values indicate population growth, while negative values indicate decline.
• It allows us to analyze and measure changes over time efficiently.

Deciphering Rate of Change

Rate of change is a term used to describe how quickly a certain quantity changes over time. When it comes to populations, this is where the growth rate function, derived from the population function, becomes essential.

The growth rate function is simply the derivative of the population function. This tells us how rapidly the population size is changing at any instant. If the rate is positive, the population is increasing; if negative, it's decreasing.

• **Rate of change provides vital insights**: Knowing how fast the population changes can inform resource management and strategic planning.
• **It's a dynamic measure**: It may vary as the drivers behind population changes, like birth rates and death rates, fluctuate over time.
• **Comparing rates**: Understanding how different factors influence rate of change can lead to better forecasting and mitigation strategies.

Interpreting Decreasing Growth Rate

The idea of a decreasing growth rate might initially seem confusing, especially if the population function is increasing. However, this simply means that the population is still growing, just at a slower pace over time.

Imagine running a race where you start quickly but gradually slow down while still moving forward. Similarly, a decreasing growth rate signifies that the population's speed of growth is reducing. The growth rate function remains positive, hence the population increases, though the rate at which it increases is declining.

In our example, \( \frac{dP}{dt} = 1000( \frac{2t}{t^2 + 1} - \frac{2t^3}{(t^2 + 1)^2}) \) is always positive for all \( t \), yet the expression diminishes as \( t \) grows larger.

• Positive but decreasing growth rates indicate continued expansion albeit at a lessening pace.
• This concept is important for understanding population dynamics over longer periods.
• A dwindling growth rate might require adjustments in planning and resource allocation.