Problem 24 - College Algebra and Calculus: An Applied Approach

Question

Write the rational expression in simplest form.\(\frac{3-x}{8 x-24}\)

Step-by-Step Solution

Answer

The simplified form of the given rational expression is -\frac{1}{8}.

Step 1: Rearrange the numerator and denominator

Rewrite the numerator \(3-x\) as \(-1*(x-3)\) and the denominator \(8x-24\) as \(8*(x-3)\). So, the expression becomes \(\frac{-1*(x-3)}{8*(x-3)}\).

Step 2: Simplify the expression

Now, \(x - 3\) is a common factor in both the numerator and the denominator. We can cancel out these common factors. So, the simplified expression becomes \(-\frac{1}{8}\).

Key Concepts

Algebraic Manipulation

Understanding algebraic manipulation is essential when working with equations and expressions in mathematics. It involves rearranging and simplifying complex algebraic expressions to a more manageable form. This typically includes operations such as adding, subtracting, multiplying, and dividing terms, as well as factoring polynomials and canceling common factors.

In the exercise \(\frac{3-x}{8 x-24}\), algebraic manipulation begins with reordering the terms in the numerator to \(x-3\). This is done by factoring out a negative sign, effectively changing \(3 - x\) to \( -1 \times (x - 3)\). Similarly, the denominator is factored to \(8 \times (x - 3)\). This type of manipulation sets the stage for simplification by revealing common factors.

Common Factors

Identifying common factors plays a pivotal role in simplifying rational expressions. A common factor is a term or polynomial that is present in both the numerator and the denominator of a fraction.

In our example, after the algebraic manipulation, we observe that \(x-3\) is present in both the numerator and the denominator. Recognizing and canceling out these common factors can dramatically simplify an expression. It's like simplifying the fraction \(\frac{4}{8}\) to \(\frac{1}{2}\) by dividing both the numerator and the denominator by 4, their greatest common factor.

Exercise Improvement Advice:

To help students recognize common factors, it's beneficial to practice by finding the greatest common factor of various terms and polynomials through factorization exercises.

Rational Expression Simplification

The goal of rational expression simplification is to reduce the complexity of an expression without changing its value. This process often requires a combination of the previously mentioned techniques: algebraic manipulation and identifying common factors.

Once common factors are found, as in the expression \(\frac{-1 \times (x-3)}{8 \times (x-3)}\), they can be canceled out. It's important to note that factors can only be canceled if they are multiplied together, not when they're added or subtracted.

Cancelable factors are often highlighted by factoring techniques, which transform an expression into a product of its factors. The resulting simplification in our example led to \(\frac{-1}{8}\), which is much simpler and easier to work with than the original expression.

Understanding Simplification:

It's essential to grasp that simplification is not about altering the fundamental value but presenting it in its most uncomplicated form.