Problem 46 - Applied Mathematics: For the Managerial, Life, and Social Sciences

Question

Find the values of \(x\) for which each function is continuous. \(f(x)=x^{3}-2 x^{2}+x-1\)

Step-by-Step Solution

Answer

The function \(f(x) = x^3 - 2x^2 + x - 1\) is a polynomial function, which is continuous for all values of \(x\). Therefore, the function is continuous for all \(x\).

Step 1: Identify the type of function

The function \(f(x) = x^3 - 2x^2 + x - 1\) is a polynomial function of degree 3.

Step 2: Determine the continuity of polynomial functions

Polynomial functions are continuous for all values of x.

Step 3: Conclusion

The function \(f(x) = x^3 - 2x^2 + x - 1\) is continuous for all values of x.

Key Concepts

Polynomial Functions

A polynomial function is a mathematical expression involving a sum of powers in one or more variables multiplied by coefficients. These functions are often represented in the general form: \[P(x) = a_nx^n + a_{n-1}x^{n-1} + \ldots + a_1x + a_0\]where \(a_n, a_{n-1}, \ldots, a_0\) are constants and \(n\) is a non-negative integer representing the degree of the polynomial. By nature, polynomial functions consist of basic algebraic operations including addition, subtraction, and multiplication, exclusively using non-negative integer exponents.

• Examples: \(x^2 - 4x + 4\), \(3x^3 + 2x^2 - x + 5\)
• Non-examples: \( \frac{1}{x} \), \(\sqrt{x}\)

Understanding polynomial functions is foundational because they are simple enough to easily analyze, yet versatile enough to model a wide array of natural phenomena.

Degree of Polynomial

The degree of a polynomial is one of the key characteristics that define its behavior. It refers to the highest power of the variable within the polynomial expression. Let’s break down the polynomial \(f(x) = x^3 - 2x^2 + x - 1\):

• The term \(x^3\) is the one with the highest power.
• Hence, the degree of this polynomial is 3.

This degree indicates several properties of the polynomial:

• Number of roots: A polynomial of degree \(n\) can have up to \(n\) roots.
• Terms: As you add terms like \(x^2\), \(x\), and constants, the degree doesn’t change unless you include a higher power term.
• Graph behavior: It profoundly influences the shape and direction of the graph, with the number of turning points being at most \(n-1\).

Remember, identifying the degree is crucial for understanding the overall structure of a polynomial function.

Continuous Functions

A function is termed 'continuous' if its graph can be drawn without lifting a pencil from the paper. Specifically, a function is continuous at a point \(x = a\) if:

• The function is defined at \(x = a\).
• The limit of the function as \(x\) approaches \(a\) exists.
• The limit of the function equals the function's value at \(x = a\).

For polynomial functions, like our example function \(f(x) = x^3 - 2x^2 + x - 1\), continuity is inherent across all real numbers. This is due to their smooth and unbroken nature. Here are some reasons why polynomial functions are continuous:

• Polynomial functions consist only of integer powers, meaning their graph is smooth.
• They lack breaks, holes, or jumps in their domain and range.
• This inherent continuity makes them reliable models for real-world applications.

Understanding the continuity of polynomial functions helps set a solid foundation for higher-level calculus concepts, where continuity plays a critical role.