Chapter 10: Problem 35
Use the Binomial Theorem to expand the given expression. $$ \left(x^{2}-y^{2}\right)^{3} $$
Short Answer
Expert verified
The expanded form is \( x^6 - 3x^4y^2 + 3x^2y^4 - y^6 \).
Step by step solution
01
Identify the Components
The given expression is \( (x^2 - y^2)^3 \). The binomial theorem states that \( (a + b)^n = \sum_{k=0}^{n} \binom{n}{k} a^{n-k} b^k \). Here, \( a = x^2 \), \( b = -y^2 \), and \( n = 3 \).
02
Calculate Binomial Coefficients
For \( n = 3 \), the relevant binomial coefficients are \( \binom{3}{0} = 1 \), \( \binom{3}{1} = 3 \), \( \binom{3}{2} = 3 \), and \( \binom{3}{3} = 1 \). These can be calculated using the formula \( \binom{n}{k} = \frac{n!}{k!(n-k)!} \).
03
Apply the Binomial Theorem
Expand the expression using the binomial theorem: \[(x^2 - y^2)^3 = \sum_{k=0}^{3} \binom{3}{k} (x^2)^{3-k}(-y^2)^k \]. This becomes:\[\begin{align*}&= \binom{3}{0}(x^2)^3(-y^2)^0 + \binom{3}{1}(x^2)^2(-y^2)^1 + \binom{3}{2}(x^2)^1(-y^2)^2 + \binom{3}{3}(x^2)^0(-y^2)^3. \&= 1 \cdot (x^6) + 3 \cdot (x^4)(-y^2) + 3 \cdot (x^2)(y^4) - 1 \cdot (y^6).\end{align*}\]
04
Simplify Each Term
Simplify the expression by calculating each term:1. \( 1 \cdot x^6 = x^6 \)2. \( 3 \cdot x^4 \cdot (-y^2) = -3x^4y^2 \)3. \( 3 \cdot x^2 \cdot y^4 = 3x^2y^4 \)4. \( -1 \cdot y^6 = -y^6 \).
05
Write the Final Expanded Form
Combine the simplified terms to find the final expanded expression:\( x^6 - 3x^4y^2 + 3x^2y^4 - y^6 \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Polynomial Expansion
The process of polynomial expansion involves expressing a power of a binomial (two terms combined by addition or subtraction) as a polynomial - a sum of terms made from the variables and constants in the expression. For the expression \((x^2 - y^2)^3\), polynomial expansion helps us write it as a series of terms using the Binomial Theorem. This theorem provides a formula to expand expressions of the form \((a + b)^n\) into a sum of terms, each with a specific coefficient. Using the Binomial Theorem, \((x^2 - y^2)^3\) is expanded into terms like \(x^6\), \(-3x^4y^2\), \(3x^2y^4\), and \(-y^6\). By expanding complex expressions, each term is clearly defined, making the expression easier to work with for further mathematical operations.
Binomial Coefficients
Binomial coefficients play a crucial role in polynomial expansion using the Binomial Theorem. These coefficients determine the weight of each term in the expansion process. They are represented as \(\binom{n}{k}\), which you can calculate using factorials:
- \(\binom{n}{k} = \frac{n!}{k!(n-k)!}\)
Exponentiation
Exponentiation refers to the mathematical operation involving numbers raised to a power. In the context of polynomial expansion, exponentiation is used to calculate the powers of binomial terms according to their position in the expansion sequence. For \((x^2 - y^2)^3\), exponentiation is applied to each part of the binomial. When expanding this specific expression:
- \((x^2)\) is raised to decreasing powers: \(x^6, x^4, x^2, x^0\)
- \((-y^2)\) is raised to increasing powers: \((-y^2)^0, (-y^2)^1, (-y^2)^2, (-y^2)^3\)