Chapter 7: Problem 534
\({ }^{\mathrm{n}} \mathrm{C}_{0}-{ }^{\mathrm{n}} \mathrm{C}_{1}+{ }^{\mathrm{n}} \mathrm{C}_{2}-\cdots+(-1)^{\mathrm{n} \mathrm{n}} \mathrm{C}_{\mathrm{n}}=\) (a) 0 (b) - 1 (c) \(\mathrm{n}\) (d) 1
Short Answer
Expert verified
\( { }^{n} C_{0} - { }^{n} C_{1} + { }^{n} C_{2} - \cdots + (-1)^{n} { }^{n} C_{n} = 0 \)
Step by step solution
01
Recall the binomial theorem expansion
The binomial theorem states that for any positive integer n and any real numbers x and y, the expansion of \((x+y)^n\) can be represented as:
\[
(x+y)^n = { }^{n} C_{0} x^n y^0 + { }^{n} C_{1} x^{n-1} y^1 + { }^{n} C_{2} x^{n-2} y^2 + \cdots + { }^{n} C_{n} x^0 y^n
\]
02
Substitute x and y in the binomial theorem
To derive the given expression, substitute \(x = 1\) and \(y = -1\) in the binomial theorem expansion. This will result in:
\[
(1 + (-1))^n = { }^{n} C_{0} 1^{n} (-1)^0 - { }^{n} C_{1} 1^{n-1} (-1)^1 + { }^{n} C_{2} 1^{n-2} (-1)^2 - \cdots + (-1)^{n} { }^{n} C_{n} 1^0 (-1)^n
\]
03
Simplify the equation
Simplify the equation from Step 2. The terms with \(1\) as the base to any power will remain the same. We get:
\[
0^n = { }^{n} C_{0} - { }^{n} C_{1} + { }^{n} C_{2} - \cdots + (-1)^{n} { }^{n} C_{n}
\]
Since \(0^n = 0\) for \(n \ge 1\), the expression becomes:
\[
0 = { }^{n} C_{0} - { }^{n} C_{1} + { }^{n} C_{2} - \cdots + (-1)^{n} { }^{n} C_{n}
\]
04
Compare with the given choices
We can now see that the given expression is equal to 0, which corresponds to choice (a):
\[
{ }^{n} C_{0} - { }^{n} C_{1} + { }^{n} C_{2} - \cdots + (-1)^{n} { }^{n} C_{n} = 0
\]
Thus, the correct answer is (a) 0.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Binomial Theorem Expansion
The Binomial Theorem provides a powerful shortcut for expanding algebraic expressions raised to any power. Specifically, it allows us to write the expression \( (x + y)^n \) as a sum of terms involving the powers of x and y, each accompanied by a particular binomial coefficient. When you come across \( (x + y)^n \), the theorem gives you a clear-cut way to write it as \[ (x+y)^n = { }^{n} C_{0} x^n y^0 + { }^{n} C_{1} x^{n-1} y^1 + { }^{n} C_{2} x^{n-2} y^2 + \cdots + { }^{n} C_{n} x^0 y^n \]
To fully grasp this concept, think of the expansion as a multi-layered cake. Each layer represents a term in the expansion, and the binomial coefficients (like \( { }^{n} C_{k} \)) are like precise measurements for the ingredients that guarantee the cake comes out just perfect. Knowing how to use and calculate these coefficients is crucial in algebra and will serve as a foundation for more complex operations in math.
To fully grasp this concept, think of the expansion as a multi-layered cake. Each layer represents a term in the expansion, and the binomial coefficients (like \( { }^{n} C_{k} \)) are like precise measurements for the ingredients that guarantee the cake comes out just perfect. Knowing how to use and calculate these coefficients is crucial in algebra and will serve as a foundation for more complex operations in math.
Combinatorics
At the heart of the Binomial Theorem lies Combinatorics, the area of mathematics concerned with counting. It is the study of how to count objects in a systematic way. For instance, the binomial coefficients encountered in the binomial expansion represent the number of ways to choose k elements out of a set of n elements, written as \( { }^{n} C_{k} \).
Imagine you have a set of n different books and you want to know in how many ways you can choose k books to take on a vacation. Combinatorics provides the tools to find this number without having to list out all the possible combinations. This mathematical toolkit is incredibly useful in fields like statistics, computer science, and even biology for studying combinations and permutations of various elements.
Imagine you have a set of n different books and you want to know in how many ways you can choose k books to take on a vacation. Combinatorics provides the tools to find this number without having to list out all the possible combinations. This mathematical toolkit is incredibly useful in fields like statistics, computer science, and even biology for studying combinations and permutations of various elements.
Binomial Coefficients
The coefficients in the expansion of the binomial theorem, aptly named Binomial Coefficients, serve as a bridge between algebra and combinatorics. Each coefficient \( { }^{n} C_{k} \) is a numerical value that indicates the number of combinations of n items taken k at a time. They are a key component in the binomial theorem and can be calculated using the formula: \[ { }^{n} C_{k} = \frac{n!}{k! (n-k)!} \]
Think of binomial coefficients as the number of different groups you can form. For example, if you're picking teams for a game, the coefficient tells you how many ways you can create a team of k players from a larger group of n players. Binomial coefficients are not just theoretical numbers; they have practical implications in lottery probabilities, game theory, and even in constructing Pascal's Triangle, where these coefficients neatly line up row after row.
Think of binomial coefficients as the number of different groups you can form. For example, if you're picking teams for a game, the coefficient tells you how many ways you can create a team of k players from a larger group of n players. Binomial coefficients are not just theoretical numbers; they have practical implications in lottery probabilities, game theory, and even in constructing Pascal's Triangle, where these coefficients neatly line up row after row.
Algebraic Expressions
The ability to understand and manipulate Algebraic Expressions is fundamental in exploring the Binomial Theorem and its applications. An algebraic expression is a mathematical phrase that can contain numbers, variables, and operators. They are the sentences of the mathematical language, allowing us to communicate and solve problems involving unknown values.
When dealing with algebraic expressions like the binomial expansion \( (x + y)^n \), you’re essentially playing with building blocks, combining and recombining them to form new expressions. They can represent real-world quantities such as distance, area, volume, and with the Binomial Theorem, they provide a swift means to expand expressions without laboriously multiplying the terms one by one. Mastering algebraic expressions is thus a stepping stone to tackling more intricate math problems effortlessly.
When dealing with algebraic expressions like the binomial expansion \( (x + y)^n \), you’re essentially playing with building blocks, combining and recombining them to form new expressions. They can represent real-world quantities such as distance, area, volume, and with the Binomial Theorem, they provide a swift means to expand expressions without laboriously multiplying the terms one by one. Mastering algebraic expressions is thus a stepping stone to tackling more intricate math problems effortlessly.