Chapter 11: Problem 59
Write the complete binomial expansion for each of the following powers of a binomial. $$\left(x^{2}+1\right)^{4}$$
Short Answer
Expert verified
\(((x^2 + 1)^4 = x^{8} + 4x^{6} + 6x^{4} + 4x^{2} + 1).\)
Step by step solution
01
Identify the Binomial
The given binomial to be expanded is \((x^2 + 1)^{4}\).
02
Understand the Binomial Theorem
The Binomial Theorem states that \((a+b)^n = \sum_{k=0}^{n} \binom{n}{k} a^{n-k} b^{k}\). In this case, \(a = x^2\), \(b = 1\), and \(n = 4\).
03
Expand Using the Binomial Theorem
Apply the theorem to expand \((x^2 + 1)^{4}\) by substituting \(a, b, \text{ and } n\): \[((x^2 + 1)^{4} = \sum_{k=0}^{4} \binom{4}{k} (x^2)^{4-k} (1)^{k}).\]
04
Calculate the Binomial Coefficients
Compute the binomial coefficients \(\binom{4}{k}\) for \(k = 0 \text{ to } 4\). These are: \binom{4}{0} = 1, \binom{4}{1} = 4, \binom{4}{2} = 6, \binom{4}{3} = 4, \text{ and } \binom{4}{4} = 1.\
05
Substitute and Simplify Each Term
Replace the binomial coefficients and simplify each term: \(\binom{4}{0} (x^2)^4 (1)^0 = x^{8}\), \(\binom{4}{1} (x^2)^3 (1)^1 = 4x^{6}\), \(\binom{4}{2} (x^2)^2 (1)^2 = 6x^{4}\), \(\binom{4}{3} (x^2)^1 (1)^3 = 4x^{2}\), and \(\binom{4}{4} (x^2)^0 (1)^4 = 1\).
06
Write the Entire Expansion
Combine all the terms to write the complete binomial expansion: \(((x^2 + 1)^4 = x^{8} + 4x^{6} + 6x^{4} + 4x^{2} + 1).\)
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
The Binomial Theorem
The Binomial Theorem is a foundational concept in algebra, providing a method for expanding powers of a binomial. A binomial is simply an algebraic expression with two terms, like \((a + b)\). The theorem states that for any positive integer \(n\), the expansion of \((a + b)^n\) can be given by a sum of terms involving binomial coefficients, written mathematically as:
\((a + b)^n = \sum_{k=0}^{n} \binom{n}{k} a^{n-k} b^{k}\).
Each term in this formula has:
- a binomial coefficient \( \binom{n}{k} \),
- a power of \(a\) that decreases from \(n\) to 0,
- and a power of \(b\) that increases from 0 to \(n\).
This enables us to systematically expand any binomial raised to a power.
\((a + b)^n = \sum_{k=0}^{n} \binom{n}{k} a^{n-k} b^{k}\).
Each term in this formula has:
- a binomial coefficient \( \binom{n}{k} \),
- a power of \(a\) that decreases from \(n\) to 0,
- and a power of \(b\) that increases from 0 to \(n\).
This enables us to systematically expand any binomial raised to a power.
Binomial Coefficients
Binomial coefficients are the numbers that appear in the expansions of binomials and are represented using the notation \(( \binom{n}{k} \)).
These coefficients can be calculated using the formula: \(\binom{n}{k} = \frac{n!}{k!(n-k)!}\)
where \(n! \) (n factorial) is the product of all integers from 1 to \(n\).
In the context of our example \(\binom{4}{k}\), we have:
These coefficients can be calculated using the formula: \(\binom{n}{k} = \frac{n!}{k!(n-k)!}\)
where \(n! \) (n factorial) is the product of all integers from 1 to \(n\).
In the context of our example \(\binom{4}{k}\), we have:
- \(\binom{4}{0} = 1 \)
- \(\binom{4}{1} = 4 \)
- \(\binom{4}{2} = 6 \)
- \(\binom{4}{3} = 4 \)
- \(\binom{4}{4} = 1 \)
Mathematics Education
Understanding the Binomial Theorem is crucial in mathematics education. It involves a mix of concepts such as permutations, combinations, and factorials, providing a comprehensive exercise in algebra.By studying the binomial theorem, students learn to:
- Recognize the structure of algebraic expressions
- Use factorial notation and calculations
- Break down complex problems into smaller steps
- Identifying the components of the binomial
- Calculating binomial coefficients
- Substituting values and simplifying expressions