Chapter 13: Problem 10
Use Pascal’s triangle to expand the expression. $$ (\sqrt{a}+\sqrt{b})^{6} $$
Short Answer
Expert verified
\(a^{3} + 6a^{2.5}b^{0.5} + 15a^{2}b + 20a^{1.5}b^{1.5} + 15ab^{2} + 6a^{0.5}b^{2.5} + b^{3}\)
Step by step solution
01
Identify the Row of Pascal's Triangle
We need to expand \((\sqrt{a} + \sqrt{b})^6\). First, identify the 6th row of Pascal's Triangle, which gives us the coefficients for the expansion. The 6th row is: 1, 6, 15, 20, 15, 6, 1.
02
Determine the Terms
Each term in the expansion follows the form: \( \binom{n}{k} \cdot (\sqrt{a})^{n-k} \cdot (\sqrt{b})^{k} \). For \((\sqrt{a} + \sqrt{b})^6\), each term will have exponent sums equal to 6.
03
Write the Expanded Form
Using the coefficients from Pascal's Triangle and alternating powers of \(\sqrt{a}\) and \(\sqrt{b}\), write the expanded form:1. \(1 \cdot (\sqrt{a})^{6}\)2. \(6 \cdot (\sqrt{a})^{5} \cdot (\sqrt{b})^{1}\)3. \(15 \cdot (\sqrt{a})^{4} \cdot (\sqrt{b})^{2}\)4. \(20 \cdot (\sqrt{a})^{3} \cdot (\sqrt{b})^{3}\)5. \(15 \cdot (\sqrt{a})^{2} \cdot (\sqrt{b})^{4}\)6. \(6 \cdot (\sqrt{a})^{1} \cdot (\sqrt{b})^{5}\)7. \(1 \cdot (\sqrt{b})^{6}\)Let's write each term clearly in the expanded form.
04
Calculate Each Term and Simplify
Now simplify the powers and calculate:1. \((\sqrt{a})^{6} = a^{3}\)2. \(6 \cdot (\sqrt{a})^{5} \cdot (\sqrt{b})^{1} = 6a^{2.5}b^{0.5}\)3. \(15 \cdot (\sqrt{a})^{4} \cdot (\sqrt{b})^{2} = 15a^{2}b\)4. \(20 \cdot (\sqrt{a})^{3} \cdot (\sqrt{b})^{3} = 20a^{1.5}b^{1.5}\)5. \(15 \cdot (\sqrt{a})^{2} \cdot (\sqrt{b})^{4} = 15ab^{2}\)6. \(6 \cdot (\sqrt{a})^{1} \cdot (\sqrt{b})^{5} = 6a^{0.5}b^{2.5}\)7. \((\sqrt{b})^{6} = b^{3}\)
05
Combine to Get the Final Expansion
Combine all the terms together:\[a^{3} + 6a^{2.5}b^{0.5} + 15a^{2}b + 20a^{1.5}b^{1.5} + 15ab^{2} + 6a^{0.5}b^{2.5} + b^{3}\]
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Binomial Expansion
Binomial expansion is a method used to expand expressions of the form \((x + y)^n\), where \(x\) and \(y\) are any expressions and \(n\) is a positive integer. The coefficients of the expansion are given by the binomial coefficients, which can be found using Pascal's Triangle. Each coefficient in Pascal’s Triangle corresponds to a term in the binomial expansion.For example, when expanding \((\sqrt{a} + \sqrt{b})^6\), we obtain:
- First, identify the 6th row of Pascal's triangle: 1, 6, 15, 20, 15, 6, 1.
- Each term in the expansion takes the form \(\binom{n}{k} \cdot (\text{first term})^{n-k} \cdot (\text{second term})^{k}\). In our example, the first term is \(\sqrt{a}\) and the second term is \(\sqrt{b}\).
Powers and Exponents
Powers and exponents are fundamental concepts in mathematics that describe how many times a number, known as the base, is multiplied by itself. In the expression \((\sqrt{a} + \sqrt{b})^6\), both \(\sqrt{a}\) and \(\sqrt{b}\) are bases raised to different powers throughout the expansion process.Understanding powers and exponents allows you to simplify expressions and solve equations more effectively:
- If a number is raised to an exponent, for instance, \(a^3\), it means \(a\) is used as a factor three times: \(a \cdot a \cdot a\).
- When raising a power to another power, you multiply the exponents: \((a^m)^n = a^{m \cdot n}\).
- For fractional exponents, like \(a^{1/2}\), the base is subject to a root: \(a^{1/2} = \sqrt{a}\).
Algebraic Expressions
Algebraic expressions consist of variables, constants, and operations (such as addition, subtraction, multiplication, and division). They can represent real-world quantities, solve equations, or model problems. Understanding algebraic expressions is necessary for manipulating and solving them correctly.When working with algebraic expressions in the binomial expansion, considering terms like \(6a^{2.5}b^{0.5}\), there's a need to manage both numbers and variables efficiently:
- Variables represent unknowns and are crucial for forming expressions. In our example, terms are written in terms of \(a\) and \(b\).
- Understanding how to expand, condense, and simplify can uncover the essence of expressions and equations.
- During binomial expansion, the combination of coefficients and variables demands a careful handling of algebraic properties.