Chapter 11: Problem 70
Use the binomial theorem to expand each expression. See Example 7. $$ (2 m+3 n)^{5} $$
Short Answer
Expert verified
The expanded expression is \(32m^5 + 240m^4n + 720m^3n^2 + 1080m^2n^3 + 810mn^4 + 243n^5\).
Step by step solution
01
Understand the Binomial Theorem
The binomial theorem states that \((a + b)^n = \sum_{k=0}^{n} \binom{n}{k} a^{n-k} b^k\). This theorem allows us to expand expressions that are raised to a power, such as \((2m + 3n)^5\).
02
Identify Terms in the Binomial
In the expression \((2m + 3n)^5\), identify \(a = 2m\) and \(b = 3n\), and \(n = 5\). These values will be used in the binomial expansion formula.
03
Calculate Binomial Coefficients
Calculate each of the binomial coefficients \(\binom{5}{k}\) for \(k = 0, 1, 2, 3, 4, 5\) using the formula \(\binom{n}{k} = \frac{n!}{k!(n-k)!}\).
04
Expand the Binomial
Use the binomial theorem to expand: \((2m + 3n)^5 = \sum_{k=0}^{5} \binom{5}{k} (2m)^{5-k} (3n)^k\).Calculate each term separately.
05
Compute Each Term
- For \(k=0\): \(\binom{5}{0} (2m)^5 (3n)^0 = 1 \cdot 32m^5 \cdot 1 = 32m^5\).- For \(k=1\): \(\binom{5}{1} (2m)^4 (3n)^1 = 5 \cdot 16m^4 \cdot 3n = 240m^4n\).- For \(k=2\): \(\binom{5}{2} (2m)^3 (3n)^2 = 10 \cdot 8m^3 \cdot 9n^2 = 720m^3n^2\).- For \(k=3\): \(\binom{5}{3} (2m)^2 (3n)^3 = 10 \cdot 4m^2 \cdot 27n^3 = 1080m^2n^3\).- For \(k=4\): \(\binom{5}{4} (2m)^1 (3n)^4 = 5 \cdot 2m \cdot 81n^4 = 810mn^4\).- For \(k=5\): \(\binom{5}{5} (2m)^0 (3n)^5 = 1 \cdot 1 \cdot 243n^5 = 243n^5\).
06
Write the Expanded Expression
Combine all the terms: \( (2m + 3n)^5 = 32m^5 + 240m^4n + 720m^3n^2 + 1080m^2n^3 + 810mn^4 + 243n^5 \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Binomial Expansion
The binomial expansion is a crucial concept in algebra that helps expand expressions raised to a power, fitting the form \(a + b\)^n. This process utilizes the Binomial Theorem, which simplifies the multiplication of binomials without directly performing repetitive multiplication. Instead of manually expanding, the theorem provides a systematic way to generate each term in the resulting expression.
For example, when you have the expression \(2m + 3n\)^5, the binomial expansion allows us to easily determine each term of this higher power of a binomial. This step-by-step method leverages both algebraic computation and combinatorial mathematics, turning a complex task into a manageable process.
For example, when you have the expression \(2m + 3n\)^5, the binomial expansion allows us to easily determine each term of this higher power of a binomial. This step-by-step method leverages both algebraic computation and combinatorial mathematics, turning a complex task into a manageable process.
- Start by identifying the components \(a, b\), and the exponent \(n\).
- Calculate binomial coefficients, which are essential to determine the weight of each term in the series.
- Compute each term using the formula with these coefficients and the identified components.
Binomial Coefficients
Binomial coefficients play a vital role in the binomial expansion, as they determine the contribution of each term in the expanded expression. These coefficients are represented by \binom{n}{k}\, which translates to 'n choose k' and signifies the number of ways to choose \(k\) items from a total of \(n\) items.
To calculate these coefficients, the formula \binom{n}{k} = \frac{n!}{k!(n-k)!}\ is used, where \(n!\) denotes the factorial of \(n\). Factorials represent the product of all positive integers up to a specified number, providing a means of computing combinations efficiently.
To calculate these coefficients, the formula \binom{n}{k} = \frac{n!}{k!(n-k)!}\ is used, where \(n!\) denotes the factorial of \(n\). Factorials represent the product of all positive integers up to a specified number, providing a means of computing combinations efficiently.
- Each binomial coefficient directly influences the corresponding term in the binomial expansion.
- The sum of the exponents in each term matches the original power, ensuring the identity of the expression remains intact.
- For \(k = 0, 1, ... , n\), calculate \binom{n}{k}\ to ensure accurate expansion.
Polynomial Expansion
Polynomial expansion refers to the process of expressing a polynomial that is in a compact form, like \(a + b\)^n, into an expanded form that comprises a sum of terms. Each term includes variables raised to certain powers, multiplied by coefficients.
In the context of the binomial theorem, polynomial expansion provides a method to systematically express these products where each term of the expanded polynomial is a combination of the original binomial's terms. It essentially uncovers the underlying structure and connections between terms.
In the context of the binomial theorem, polynomial expansion provides a method to systematically express these products where each term of the expanded polynomial is a combination of the original binomial's terms. It essentially uncovers the underlying structure and connections between terms.
- Identify each term's coefficient using binomial coefficients.
- Determine the power for each component by maintaining the sum equal to the original exponent, \(n\).
- Write each term considering both the coefficients and powers of variables, like \((2m)^{n-k} (3n)^k\).