Chapter 5: Problem 55
Find a polynomial function with the given real zeros whose graph contains the given point. Zeros: -1 (multiplicity 2), 1 (multiplicity 2) Degree 4 Point: (-2,45)
Short Answer
Expert verified
The polynomial function is f(x) = 5(x^4 - 2x^2 + 1).
Step by step solution
01
Identify the Polynomial Form
Given the zeros -1 (multiplicity 2) and 1 (multiplicity 2), the polynomial can be written as: f(x) = a(x + 1)^2(x - 1)^2
02
Expand the Polynomial
Expand (x + 1)^2(x - 1)^2: (x + 1)^2 = x^2 + 2x + 1 (x - 1)^2 = x^2 - 2x + 1 Using distribution: f(x) = a(x^2 + 2x + 1)(x^2 - 2x + 1)
03
Simplify the Polynomial
Use the distribution to expand and simplify the polynomial: f(x) = a(x^2(x^2 - 2x + 1) + 2x(x^2 - 2x + 1) + 1(x^2 - 2x + 1)) f(x) = a(x^4 - 2x^3 + x^2 + 2x^3 - 4x^2 + 2x + x^2 - 2x + 1) f(x) = a(x^4 - 2x^2 + 1)
04
Determine the Coefficient 'a'
Substitute the point (-2, 45) into the polynomial to find 'a': 45 = a((-2)^4 - 2(-2)^2 + 1) 45 = a(16 - 8 + 1) 45 = a(9) a = 5
05
Write the Final Polynomial
Substitute 'a' back into the polynomial: f(x) = 5(x^2 + 2x + 1)(x^2 - 2x + 1) After expansion and simplification: f(x) = 5(x^4 - 2x^2 + 1)
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
real zeros
In polynomial functions, real zeros are the x-values where the polynomial equals zero. These are the points where the graph of the function crosses or touches the x-axis. Identifying the real zeros of a polynomial is essential for sketching its graph and solving equations.
**Key Points to Remember about Real Zeros**
**Key Points to Remember about Real Zeros**
- Real zeros are found by solving the equation f(x) = 0.
- Each zero represents an x-value where the polynomial crosses the x-axis.
- Real zeros can be repeated, impacting the shape of the graph.
multiplicity of zeros
Multiplicity of zeros refers to how many times a particular zero appears in a polynomial. It indicates whether the graph of the function merely touches the x-axis at that point or actually crosses it.
**Understanding Multiplicity**
**Understanding Multiplicity**
- A zero with an **odd multiplicity** causes the graph to cross the x-axis.
- A zero with an **even multiplicity** causes the graph to touch but not cross the x-axis.
- Higher multiplicity flattens the graph at the zero.
polynomial expansion
Polynomial expansion involves distributing the factors of a polynomial to write it as a sum of its terms. This process helps in simplifying and solving polynomial equations.
**Steps in Polynomial Expansion**
\((x + 1)^2 = x^2 + 2x + 1\)
\((x - 1)^2 = x^2 - 2x + 1\)
Using distribution, we get:
\(a(x^2 + 2x + 1)(x^2 - 2x + 1)\)
After expansion and combining like terms, the final polynomial is simplified.
**Steps in Polynomial Expansion**
- Expand any squared or higher power terms first.
- Use the distributive property to multiply the expanded terms.
- Combine like terms to simplify the expression.
\((x + 1)^2 = x^2 + 2x + 1\)
\((x - 1)^2 = x^2 - 2x + 1\)
Using distribution, we get:
\(a(x^2 + 2x + 1)(x^2 - 2x + 1)\)
After expansion and combining like terms, the final polynomial is simplified.
finding coefficients
Finding the coefficients in a polynomial is crucial for writing the exact function. Coefficients are the constants that multiply the variables in each term of the polynomial.
**Process of Finding Coefficients**
\(45 = a((-2)^4 - 2(-2)^2 + 1) = 9a \).
Solving for 'a' gives us: \ a = 5 \.
Therefore, the final polynomial with the correct coefficient is \ f(x) = 5(x^4 - 2x^2 + 1) \.
**Process of Finding Coefficients**
- Form the expanded polynomial expression.
- Substitute the given point to solve for the leading coefficient.
- Multiply the polynomial by this coefficient.
\(45 = a((-2)^4 - 2(-2)^2 + 1) = 9a \).
Solving for 'a' gives us: \ a = 5 \.
Therefore, the final polynomial with the correct coefficient is \ f(x) = 5(x^4 - 2x^2 + 1) \.