Problem 10 - Introductory Algebra for College Students

Question

Evaluate each function at the given values. \(f(x)=x+6\) a. \(f(4)\) b. \(f(-8)\) c. \(f(0)\)

Step-by-Step Solution

Answer

For \(f(x) = x + 6\), \(f(4) = 10\), \(f(-8) = -2\), and \(f(0) = 6\).

Step 1: Evaluate \(f(4)\)

To find the value of the function at \(4\), substitute \(4\) in place of \(x\) in the function: \(f(4) = 4 + 6 = 10\). So, \(f(4) = 10\).

Step 2: Evaluate \(f(-8)\)

To find the value of the function at \(-8\), substitute \(-8\) in place of \(x\) in the function: \(f(-8) = -8 + 6 = -2\). So, \(f(-8) = -2\).

Step 3: Evaluate \(f(0)\)

To find the value of the function at \(0\), substitute \(0\) in place of \(x\) in the function: \(f(0) = 0 + 6 = 6\). So, \(f(0) = 6\).

Key Concepts

Algebraic Functions

An algebraic function is essentially a mathematical expression that relates two variables by an equation involving algebraic operations such as addition, subtraction, multiplication, division, powers, and roots. Think of it as a rule where you put a number in, perform certain algebraic manipulations, and get a new number out. For instance, the function from the original exercise, f(x) = x + 6, is one of the simplest types of algebraic functions, a linear function, where any input x will result in an output that is x increased by 6.

One of the key characteristics of algebraic functions is that they consist of a finite number of algebraic operations. In contrast, functions that cannot be formulated with such a finite process, like sine and cosine, are known as transcendental functions. Algebraic functions are a foundational concept in algebra and are necessary to understand before moving on to more complex functions.

Substitution Method

The substitution method is a fundamental tool in algebra, allowing us to evaluate functions, solve equations, and understand how changes in one variable affect another. In essence, it involves replacing variables with either numbers or expressions to perform calculations. As seen in the provided solution, to evaluate f(x) = x + 6 at x = 4, you simply replace x with 4 and calculate the result, leading to f(4) = 4 + 6, which simplifies to 10. The power of substitution lies in its simplicity and versatility—it can be used for complex expressions and for functions involving multiple variables.

The substitution method also helps in understanding the behavior of functions as you substitute different values for the variable and notice how the output changes. This method forms the basis for more advanced topics such as solving systems of equations or analyzing functional relationships graphically.

Function Notation

Function notation is the way we represent functions in mathematics, allowing us to communicate and work with functions efficiently. It essentially gives us a shorthand to describe the action of taking an input, applying the function's rule, and finding the output. The exercise uses the function f(x) = x + 6, where f denotes the function, and x is the variable or input value. Function notation comes with a set of conventions; for example, f(4) tells us to evaluate the function f when the input is 4.

Understanding function notation is critical for students because it is used throughout higher mathematics, from calculus to advanced algebra. Additionally, it gives you a language to discuss and think clearly about mathematical functions, an essential skill in mathematical reasoning and subsequent applications in science and engineering.