Chapter 3: Problem 49
Determine whether the intermediate value theorem guarantees that the function has a zero on the given interval. \(f(x)=2 x^{3}-7 x^{2}-14 x+30\) a. [1,2] b. [2,3] c. [3,4] d. [4,5]
Short Answer
Expert verified
The intermediate value theorem guarantees a zero in intervals [1, 2] and [4, 5].
Step by step solution
01
Evaluate the function at the given interval endpoints for [1, 2]
Calculate the values of the function at the endpoints of the interval [1, 2]: \[ f(1) = 2(1)^3 - 7(1)^2 - 14(1) + 30 \] \[ f(1) = 2 - 7 - 14 + 30 = 11 \]\[ f(2) = 2(2)^3 - 7(2)^2 - 14(2) + 30 \] \[ f(2) = 16 - 28 - 28 + 30 = -10 \] Check if one value is positive and the other is negative.
02
Apply the intermediate value theorem for [1, 2]
Because \( f(1) = 11 \) and \( f(2) = -10 \) have opposite signs, according to the intermediate value theorem, there is at least one value \( c \) in the interval [1, 2] where \( f(c) = 0 \). Hence, a zero is guaranteed in this interval.
03
Evaluate the function at the given interval endpoints for [2, 3]
Calculate the values of the function at the endpoints of the interval [2, 3]: \[ f(2) = -10 \] \( (Already calculated in Step 1) \)\[ f(3) = 2(3)^3 - 7(3)^2 - 14(3) + 30 \] \[ f(3) = 54 - 63 - 42 + 30 = -21 \] Check if the values have opposite signs.
04
Apply the intermediate value theorem for [2, 3]
Because \( f(2) = -10 \) and \( f(3) = -21 \) do not have opposite signs, the intermediate value theorem does not guarantee a zero in this interval.
05
Evaluate the function at the given interval endpoints for [3, 4]
Calculate the values of the function at the endpoints of the interval [3, 4]: \[ f(3) = -21 \] \( (Already calculated in Step 3) \) \[ f(4) = 2(4)^3 - 7(4)^2 - 14(4) + 30 \] \[ f(4) = 128 - 112 - 56 + 30 = -10 \] Check if the values have opposite signs.
06
Apply the intermediate value theorem for [3, 4]
Because \( f(3) = -21 \) and \( f(4) = -10 \) do not have opposite signs, the intermediate value theorem does not guarantee a zero in this interval.
07
Evaluate the function at the given interval endpoints for [4, 5]
Calculate the values of the function at the endpoints of the interval [4, 5]: \[ f(4) = -10 \] \( (Already calculated in Step 5) \) \[ f(5) = 2(5)^3 - 7(5)^2 - 14(5) + 30 \] \[ f(5) = 250 - 175 - 70 + 30 = 35 \]Check if the values have opposite signs.
08
Apply the intermediate value theorem for [4, 5]
Because \( f(4) = -10 \) and \( f(5) = 35 \) have opposite signs, the intermediate value theorem guarantees that there is at least one value \( c \) in the interval [4, 5] where \( f(c) = 0 \). Hence, a zero is guaranteed in this interval.
Unlock Step-by-Step Solutions & Ace Your Exams!
-
Full Textbook Solutions
Get detailed explanations and key concepts
-
Unlimited Al creation
Al flashcards, explanations, exams and more...
-
Ads-free access
To over 500 millions flashcards
-
Money-back guarantee
We refund you if you fail your exam.
Over 30 million students worldwide already upgrade their learning with 91Ó°ÊÓ!
Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Polynomial Functions
Polynomial functions are expressions that involve variables raised to non-negative integer exponents. They are of the form: f(x) = a_nx^n + a_{n-1}x^{n-1} + ... + a_1x + a_0, where each coefficient a_i is a real number. The degree of the polynomial is the highest exponent, and its leading coefficient is the coefficient of the highest power.
Polynomials can be classified by their degree:
Polynomials can be classified by their degree:
- Linear polynomial: Degree 1, e.g., f(x) = 3x + 2
- Quadratic polynomial: Degree 2, e.g., f(x) = 2x^2 + 3x + 1
- Cubic polynomial: Degree 3, e.g., f(x) = x^3 - 4x + 6
Interval Evaluation
Interval evaluation involves calculating the value of a function at the endpoints of a given interval. It's commonly used with the Intermediate Value Theorem (IVT). Here’s how you do it:
- Identify the interval, for example, [a, b]
- Calculate f(a) and f(b)
- Use the results to check if f(a) and f(b) have opposite signs
Finding Zeros of Functions
Finding the zeros of a function involves identifying the values of x where f(x) = 0. There are several methods for finding zeros:
- Factoring: Splitting the polynomial into products of simpler polynomials.
- Graphical Method: Plotting the function and finding the x-coordinates where the graph intersects the x-axis.
- Numerical Methods: Using algorithms like Newton-Raphson for more complicated polynomials.
College Algebra
College Algebra is a foundational mathematics course that covers a variety of essential topics. It typically includes:
- Polynomial and Rational Functions
- Exponential and Logarithmic Functions
- Systems of Equations and Inequalities
- Sequences and Series
- Basic Matrix Operations