Chapter 11: Problem 87
Expand: \(\left.(x+2 y)^{5} . \text { (Section } 10.5, \text { Examples } 2 \text { and } 3\right)\)
Short Answer
Expert verified
The expanded form of \((x + 2y)^5\) is \(x^5 + 10x^4y + 40x^3y^2 + 80x^2y^3 + 80xy^4 + 32y^5\)
Step by step solution
01
Identify the coefficients
In this case, \(a = x\) and \(b = 2y\). The power to which the binomial is raised, \(n\), is 5.
02
Apply the Binomial Theorem
Applying the binomial theorem to \((x + 2y)^5\) gives: \((a+b)^n = \binom{5}{0}x^5 (2y)^0 + \binom{5}{1}x^{4} (2y) + \binom{5}{2}x^{3} (2y)^2 + \binom{5}{3}x^{2} (2y)^3 + \binom{5}{4}x (2y)^4 + \binom{5}{5}x^0 (2y)^5\)
03
Compute the Binomial Coefficients
Next we calculate the binomial coefficients, which are: \(\binom{5}{0} = 1\), \(\binom{5}{1} = 5\), \(\binom{5}{2} = 10\), \(\binom{5}{3} = 10\), \(\binom{5}{4} = 5\), \(\binom{5}{5} = 1\)
04
Substitute the Coefficients
We substitute these coefficients and simplify to get: \(1 * x^5 * 1 + 5 * x^4 * 2y + 10 * x^3 * (2y)^2 + 10 * x^2 * (2y)^3 + 5 * x * (2y)^4 + 1 * (2y)^5\)
05
Simplify the Expression
Finally, we simplify the expression to obtain: \(x^5 + 10x^4y + 40x^3y^2 + 80x^2y^3 + 80xy^4 + 32y^5\)
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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 process which allows us to expand expressions that are raised to a power. When you encounter a binomial like \((x+2y)^5\), this means an expression with two terms where each term can be raised to a certain power, in this case, 5. This concept is rooted deeply in the Binomial Theorem, a powerful algebraic method.
The Binomial Theorem states that:
The Binomial Theorem states that:
- \((a+b)^n = \sum_{k=0}^{n} \binom{n}{k} a^{n-k} b^k\)
- "\(a\)" and "\(b\)" are the terms of the binomial
- \(n\) is the exponent to which the binomial is raised
- \(\binom{n}{k}\) refers to the binomial coefficient, which determines the weight of each term in the expansion
Pascal's Triangle
Pascal's Triangle is a fascinating mathematical concept that provides a simple and visual way to find the coefficients in a binomial expansion. Picture it as a triangular array where each number is the sum of the two numbers directly above it.
For example, the first few rows of Pascal’s Triangle look like this:
For example, the first few rows of Pascal’s Triangle look like this:
- Row 0: 1
- Row 1: 1, 1
- Row 2: 1, 2, 1
- Row 3: 1, 3, 3, 1
- Row 4: 1, 4, 6, 4, 1
- Row 5: 1, 5, 10, 10, 5, 1
Polynomial Expansion
A polynomial expansion is the result of applying the binomial theorem to an expression like \((x+2y)^5\), splitting it into a polynomial format. The expansion process involves substituting each term in the expansion with its corresponding binomial coefficient and simplifying.
To visualize how polynomial expansion works, let's tackle \((x+2y)^5\) step-by-step:
To visualize how polynomial expansion works, let's tackle \((x+2y)^5\) step-by-step:
- After applying the binomial theorem, each term looks like \(\binom{5}{k}x^{5-k}(2y)^k\)
- Simplification involves calculating powers of numbers (e.g., \((2y)^k\))
- Each resulting term of the expansion is added together to form the full polynomial