Chapter 4: Problem 24
Use substitution to determine whether \(2,3,\) and \(-1\) are zeros of $$f(x)=2 x^{3}-3 x^{2}+x+6$$
Short Answer
Expert verified
-1 is a zero of the function f(x).
Step by step solution
01
- Substitute 2 into the function
To determine if 2 is a zero of the function, substitute 2 into the function and solve for f(2): \[f(2) = 2(2)^3 - 3(2)^2 + 2 + 6\] Calculate the individual terms: \[2(2)^3 = 2(8) = 16\] \[-3(2)^2 = -3(4) = -12\] \[f(2) = 16 - 12 + 2 + 6 = 12\] Since f(2) = 12, 2 is not a zero of the function.
02
- Substitute 3 into the function
Next, substitute 3 into the function and solve for f(3): \[f(3) = 2(3)^3 - 3(3)^2 + 3 + 6\] Calculate the individual terms: \[2(3)^3 = 2(27) = 54\] \[-3(3)^2 = -3(9) = -27\] \[f(3) = 54 - 27 + 3 + 6 = 36\] Since f(3) = 36, 3 is not a zero of the function.
03
- Substitute -1 into the function
Finally, substitute -1 into the function and solve for f(-1): \[f(-1) = 2(-1)^3 - 3(-1)^2 + (-1) + 6\] Calculate the individual terms: \[2(-1)^3 = 2(-1) = -2\] \[-3(-1)^2 = -3(1) = -3\] \[f(-1) = -2 - 3 - 1 + 6 = 0\] Since f(-1) = 0, -1 is a zero of the function.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
substitution method
The substitution method is a straightforward approach used to determine if a specific value is a zero of a polynomial function. To do this, you substitute the value into the polynomial and evaluate the resulting expression.
If the result is zero, the value is indeed a zero of the polynomial.
Let's revisit the polynomial given in the exercise:
\( f(x) = 2x^3 - 3x^2 + x + 6 \).
To check if a number is a zero of this polynomial, substitute the number into all instances of \( x \) in the equation and simplify:
If the result is zero, the value is indeed a zero of the polynomial.
Let's revisit the polynomial given in the exercise:
\( f(x) = 2x^3 - 3x^2 + x + 6 \).
To check if a number is a zero of this polynomial, substitute the number into all instances of \( x \) in the equation and simplify:
- If \( f(2) = 0 \), then 2 is a zero of \( f(x) \).
- If \( f(3) = 0 \), then 3 is a zero of \( f(x) \).
- If \( f(-1) = 0 \), then -1 is a zero of \( f(x) \).
polynomial functions
Polynomial functions are expressions involving variables raised to whole-number exponents and coefficients. The general form of a polynomial function is:
\( f(x) = a_n x^n + a_{n-1} x^{n-1} + \cdots + a_1 x + a_0 \)
Here, \( a_n, a_{n-1}, \ldots, a_1, a_0 \) are constants, and \( x \) is the variable.
In the given exercise, the polynomial function is:
\( f(x) = 2x^3 - 3x^2 + x + 6 \)
Each term in this function represents a different degree of \( x \). The term \( 2x^3 \) has a degree of 3, \( -3x^2 \) has a degree of 2, \( x \) has a degree of 1, and \( 6 \) is the constant term (degree 0).
When solving polynomial functions, we often seek their zeros or roots, which are the values of \( x \) that make the function equal to zero. Finding the zeros helps understand the behavior of the polynomial graph and its intercepts with the x-axis.
\( f(x) = a_n x^n + a_{n-1} x^{n-1} + \cdots + a_1 x + a_0 \)
Here, \( a_n, a_{n-1}, \ldots, a_1, a_0 \) are constants, and \( x \) is the variable.
In the given exercise, the polynomial function is:
\( f(x) = 2x^3 - 3x^2 + x + 6 \)
Each term in this function represents a different degree of \( x \). The term \( 2x^3 \) has a degree of 3, \( -3x^2 \) has a degree of 2, \( x \) has a degree of 1, and \( 6 \) is the constant term (degree 0).
When solving polynomial functions, we often seek their zeros or roots, which are the values of \( x \) that make the function equal to zero. Finding the zeros helps understand the behavior of the polynomial graph and its intercepts with the x-axis.
math problem solving
Successfully solving math problems, especially those involving polynomial functions, requires a systematic approach. Here are strategies to follow:
Additionally, documenting each step, as shown in the provided solution, helps track progress and ensures no details are overlooked.
- Understand the problem: Ensure you grasp what the problem is asking. Identify the function and the values to be tested.
- Plan the solution: Decide on the method, such as using substitution to test possible zeros in this case.
- Execute the plan: Substituting the values into the polynomial and simplifying step-by-step helps you find the results.
- Verify your answer: Confirm your computational steps. If \( f(x) \) equals zero for a certain value, your solution is correct.
Additionally, documenting each step, as shown in the provided solution, helps track progress and ensures no details are overlooked.