Solve the difference equation?

In summary, the difference equation yn+1=-0.9yn can be solved in terms of the initial value y0 as yn=(-0.9)ny0. The textbook solution of yn=(-1)n(0.9)ny0 is equivalent, as it clarifies that even terms are positive and odd terms are negative. It is important to show that the solution satisfies the equation by substituting it back in.
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Solve the difference equation yn+1=-0.9yn in terms of the initial value y0.

y1=-0.9y0
y2=-0.9y1=(-0.9)2y0
yn=(-0.9)ny0
Is this the answer? Because the answer in the textbook says yn=(-1)n(0.9)ny0. Please help.
 
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  • #2
Your solution and the solution in your textbook are the same.
 
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  • #3
[tex](ab)^n= a^n b^n[/tex]
 
  • #4
The textbook wrote it that way to make it clear that even terms are positive and odd terms are negative.
 
  • #5
And, as I pointed out in your previous thread, you are not finished until you have shown that your solution does satisfy the equation. If yn= (-0.9)ny0 then -0.9yn= -0.9((-0.9)ny0)= (-0.9)n+1y0= yn+1.
 

1. What is a difference equation?

A difference equation is a mathematical equation that describes the relationship between the values of a sequence or time series at different points in time. It is used to model dynamic systems and can be used to predict future values of the sequence based on past values.

2. How do you solve a difference equation?

To solve a difference equation, you need to first determine the order of the equation (i.e. the highest power of the difference operator). Then, you can use various methods such as substitution, iteration, or transforming the equation into a linear or non-linear form to find a solution for the sequence.

3. What is the difference between a difference equation and a differential equation?

A difference equation involves discrete values of a sequence at different points in time, while a differential equation involves continuous values of a function at different points in space or time. Additionally, differential equations involve derivatives while difference equations involve differences between values.

4. Can difference equations be used to model real-world situations?

Yes, difference equations can be used to model a wide range of real-world situations such as population growth, economic trends, and physical systems. They can also be used to predict the behavior of these systems over time.

5. What are some applications of solving difference equations?

Solving difference equations has many practical applications in fields such as engineering, economics, biology, and physics. It can be used to analyze and predict the behavior of dynamic systems and make informed decisions based on the results.

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