How do I determine behavior of y at infinity for a given differential equation?

In summary, the conversation discusses drawing a direction field for the given differential equation y'=-1-2y and determining the behavior of y as t goes to infinity based on the direction field. It is mentioned that the direction field is a graph in an xy-coordinate system and t does not affect it. The slope at each point can be easily drawn since it only depends on x.
  • #1
Punchlinegirl
224
0
Draw a direction field for the given differential equation. Based on the the direction field, determine the behavior of y at t goes to infinity. If this behavior depends on the initial value of y at t=0, describe the dependency.
y'= -1-2y


In class we did examples where we had a range. Like we were given y'=2y-3 and told to draw the direction field for -2<y<2 and -2<t<2.
So for the problem above, how would I find a range, since it wants to infinity?
 
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  • #2
"t going to infinity" doesn'g mean anything here. Your direction field is a graph in an xy-coordinate system and t doesn't have anything to do with it. At every (x, y) point, you want to draw a short vector having slope
[itex]\frac{dy}{dx}[/itex]. But you are told that the slope is -1- 2y which depends on x only. Should be easy to draw.
 

Related to How do I determine behavior of y at infinity for a given differential equation?

1. What is a directional field in differential equations?

A directional field, also known as a slope field, is a graphical representation of the behavior of a solution to a differential equation. It shows the slope of the solution at various points on a coordinate plane.

2. How is a directional field constructed?

To construct a directional field, you need to plot a series of points on a coordinate plane using the differential equation as a guide. At each point, the slope or direction of the solution is represented by a short line segment or arrow.

3. What information can be obtained from a directional field?

A directional field can provide information about the behavior of the solution to a differential equation, including the direction of the solution, the location of equilibrium points, and the presence of critical points.

4. Can a directional field help solve a differential equation?

While a directional field can provide insights into the behavior of a solution, it cannot directly solve a differential equation. However, it can be a useful tool in understanding and analyzing the solution to a differential equation.

5. How is a directional field used in real-world applications?

Directional fields are commonly used in fields such as physics and engineering to model and predict the behavior of systems over time. They can also be used in economics and biology to study population growth and other dynamic systems.

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