Chapter 5: Problem 31
For the following exercises, find the zeros and give the multiplicity of each. $$ f(x)=x^{2}(2 x+3)^{5}(x-4)^{2} $$
Short Answer
Expert verified
The zeros are 0 (multiplicity 2), \(-\frac{3}{2}\) (multiplicity 5), and 4 (multiplicity 2).
Step by step solution
01
Identify the Factors
The function given is \( f(x) = x^{2}(2x+3)^{5}(x-4)^{2} \). Note that zeros of a function occur where each factor equals zero. Thus, we identify the factors: \( x^{2} \), \((2x+3)^{5}\), and \((x-4)^{2}\).
02
Find the Zeros by Setting Each Factor to Zero
To find the zeros, set each factor equal to zero:1. For \( x^2 = 0 \), the zero is \( x = 0 \).2. For \( (2x + 3)^5 = 0 \), solve for \( x \): \( 2x + 3 = 0 \) results in \( x = -\frac{3}{2} \).3. For \( (x - 4)^2 = 0 \), solve for \( x \): \( x - 4 = 0 \) results in \( x = 4 \).
03
Determine the Multiplicity of Each Zero
Multiplicity refers to the exponent of each factor in the function:1. The factor \( x^2 \) indicates the zero \( x = 0 \) with multiplicity 2.2. The factor \( (2x+3)^5 \) indicates the zero \( x = -\frac{3}{2} \) with multiplicity 5.3. The factor \( (x-4)^2 \) indicates the zero \( x = 4 \) with multiplicity 2.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Zeros of a Function
To understand the concept of zeros, it's essential to recognize what they represent in the context of a function. The zeros of a function are the x-values where the function equals zero. In simpler terms, these are the points where the graph of the function crosses or touches the x-axis. To find these zeros in the given function, we have to solve the equation by setting each factor to zero. Each solution to these equations indicates a zero of the function. For example, in our original function, the factors are \( x^2 \), \((2x+3)^5\), and \((x-4)^2\). Setting each factor to zero, we find:\[ \begin{align*} 1. & \quad x^2 = 0 \Rightarrow x = 0, \2. & \quad (2x+3)^5 = 0 \Rightarrow 2x + 3 = 0 \Rightarrow x = -\frac{3}{2}, \3. & \quad (x-4)^2 = 0 \Rightarrow x - 4 = 0 \Rightarrow x = 4. \end{align*} \]These values \(0, -\frac{3}{2},\) and \(4\) are the zeros of the function, signifying the x-values where the function becomes zero.
Factorization
Factorization is the process of breaking down an expression into a product of simpler factors. In polynomial functions, factorizing is an essential step to easily identify the zeros.For the function \( f(x) = x^{2}(2x+3)^{5}(x-4)^{2} \), the expression is already factorized into three distinct parts: \( x^2 \), \((2x+3)^5\), and \((x-4)^2\). These factors are simpler expressions that, when multiplied together, give the original function.Identifying these factors is crucial because each factor represents a potential zero. Specifically, each term in a factorized expression has a role in determining the fundamental traits of the function, like its zeros and their characteristics. Hence, breaking down complex polynomial expressions into factors is a fundamental step in analyzing and understanding polynomial functions.
Multiplicity of Roots
Multiplicity refers to the number of times a specific zero appears in a polynomial function. It is dictated by the exponent on the factor associated with that zero. The notion of multiplicity provides more insight into the behavior of a function around its zeros.For instance, if a zero has a multiplicity of 1, the graph of the function will cross the x-axis at that point. However, if the multiplicity is greater than 1, like 2 or 5 as in our function, the graph will touch but not necessarily cross the x-axis, creating a "bounce."In our exercise, we determined the multiplicities as follows:
- For zero \( x = 0 \), associated with the factor \( x^2 \), the multiplicity is 2.
- For zero \( x = -\frac{3}{2} \), associated with the factor \( (2x+3)^5 \), the multiplicity is 5.
- For zero \( x = 4 \), associated with the factor \( (x-4)^2 \), the multiplicity is 2.