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Use generating functions (and a computer algebra package, if available) to find the number of ways to make change for \(\$ 1\) using a) dimes and quarters. b) nickels, dimes, and quarters. c) pennies, dimes, and quarters. d) pennies, dimes, and quarters. d) pennies, nickels, dimes, and quarters.

Short Answer

Expert verified
a) 4 ways, b) 39 ways, c) 73682 ways, d) 4562 ways

Step by step solution

01

- Understand the Problem

Each scenario requires calculating the number of ways to make change for \(\$1\). \(\$1\) is equivalent to 100 cents. This will be done using generating functions for the different coin denominations.
02

- Generating Functions Explanation

Generating functions encode the number of ways to select coins to meet a specific total value. For each coin denomination, its generating function is \(1 + x^{value} + x^{2 \times value} + ...\).
03

- Part (a): Dimes and Quarters

The generating function for dimes (10 cents) is \(1 + x^{10} + x^{20} + ... = \frac{1}{1 - x^{10}}\). The generating function for quarters (25 cents) is \(1 + x^{25} + x^{50} + ... = \frac{1}{1 - x^{25}}\). The combined generating function is \(\frac{1}{(1 - x^{10})(1 - x^{25})}\).
04

- Compute Coefficient for Part (a)

Find the coefficient of \(x^{100}\) in the expansion of \(\frac{1}{(1 - x^{10})(1 - x^{25})}\). This can be computed using algebra software like Mathematica or manually expanded.
05

- Part (b): Nickels, Dimes, and Quarters

Add the generating function for nickels (5 cents): \(1 + x^{5} + x^{10} + ... = \frac{1}{1 - x^5}\). The combined generating function is \(\frac{1}{(1 - x^{5})(1 - x^{10})(1 - x^{25})}\).
06

- Compute Coefficient for Part (b)

Find the coefficient of \(x^{100}\) in \(\frac{1}{(1 - x^{5})(1 - x^{10})(1 - x^{25})}\).
07

- Part (c): Pennies, Dimes, and Quarters

Add the generating function for pennies (1 cent): \(1 + x + x^{2} + ... = \frac{1}{1 - x}\). The combined generating function is \(\frac{1}{(1 - x)(1 - x^{10})(1 - x^{25})}\).
08

- Compute Coefficient for Part (c)

Find the coefficient of \(x^{100}\) in \(\frac{1}{(1 - x)(1 - x^{10})(1 - x^{25})}\).
09

- Part (d): Pennies, Nickels, Dimes, and Quarters

Combine all four generating functions: The combined generating function is \(\frac{1}{(1 - x)(1 - x^5)(1 - x^{10})(1 - x^{25})}\).
10

- Compute Coefficient for Part (d)

Find the coefficient of \(x^{100}\) in \(\frac{1}{(1 - x)(1 - x^5)(1 - x^{10})(1 - x^{25})}\).

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

combinatorial mathematics
Combinatorial mathematics is a branch of mathematics that deals with counting, arrangement, and combination of objects. This field plays a critical role in solving problems where the number of possible configurations needs to be known. A powerful tool used within combinatorial mathematics is the generating function.
Generating functions transform sequences or problems into algebraic forms that make them easier to manipulate and solve. They are particularly useful in problems involving partitions, permutations, and combinations.
coin change problem
The coin change problem is a classic example in combinatorial mathematics. It involves finding the number of ways to make a particular amount of money with a given set of coin denominations. This problem can be tackled effectively using generating functions.
To illustrate, let's consider the task of making change for \$1\ (equivalent to 100 cents) using different combinations of coins. Each coin denomination like pennies, nickels, dimes, and quarters can be represented by its respective generating function.
For example, the generating function for dimes (10 cents) is \(\frac{1}{1 - x^{10}}\). When combined for multiple denominations, these functions allow us to calculate the number of ways to achieve the desired total.
discrete mathematics
Discrete mathematics encompasses a wide range of topics that are fundamental to computer science and mathematics. It involves studies of distinct and separable entities which include integers, graphs, and logical statements. Generating functions, as covered in combinatorial problems like the coin change problem, are a key component of discrete mathematics.
Generating functions help describe sequences and operations on these sequences in a compact form. They are not limited to simple coin change problems but are also used in more complex areas such as coding theory, network algorithms, and optimization problems. Understanding generating functions within the scope of discrete mathematics can enhance problem-solving skills and provide new insights into various applications.

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Most popular questions from this chapter

(Requires calculus) Show that if \(G_{X}\) is the probabili generating function for a random variable \(X\) such the \(X(s)\) is a nonnegative integer for all \(s \in S\) , then a) \(G_{X}(1)=1 .\) b) \(E(X)=G_{X}^{\prime}(1)\) c) \(V(X)=G_{X}^{\prime \prime}(1)+G_{X}^{\prime}(1)-G_{X}^{\prime}(1)^{2}\)

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