Modeling
Sequences
Difference eqns
100

What is mathematical modeling?

The process of converting a real-world scenario into a math problem, solving it, converting the solution back to real life, and refining the model to repeat the cycle.

100

Express the nth term of this sequence recursively:

{1, 1/3, 1/9, 1/27, ...}

a(n) = a(n-1)/3; a(0) = 1

100

In the model a(n+1) = a(n) + 0.05*a(n), which part represents the change?

0.05*a(n)

200

High-order polynomials always make great models! (True or False)

FALSE! (say why)

200

Express the nth term of this sequence iteratively:

{1, 1/3, 1/9, 1/27, ...}

a(n) = 1/3^n

200

Write a difference equation to express the change during the nth interval as a function of the previous term in the sequence.

{1, 5, 25, 125, ...}

a(n+1) - a(n) = ?

4*a(n)

300

What are the main steps of the modeling process?

1. Identify the problem.

2. State your assumptions & define your variables.

3. Figure out how the variables are related (build the model).

4. Solve the model.

5. Verify the model with external information.

6. Put the model into use.

7. Maintain the model—back to step 1!

300

Calculate a(0), a(2), and a(5) for the sequence

a(n+1) = 0.8*a(n) - 1; a(0) = 0

0, -1.8, -3.3616

300

You have a savings bond worth $1000 that accumulates interest at a rate of 1% per month. How much will it be worth after 5 years?

$1816.70

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