Chapter 7: Problem 19
Simplify each expression. See Examples 2 through 6. $$ \frac{x-7}{7-x} $$
Short Answer
Expert verified
The simplified expression is \(-1\).
Step by step solution
01
Identify the structure of the expression
Observe that the expression is a fraction with a numerator of \( x - 7 \) and a denominator of \( 7 - x \).
02
Recognize a potential simplification
Notice that the terms in the numerator \( x - 7 \) and the denominator \( 7 - x \) are similar. Specifically, \( 7 - x \) is the negative of \( x - 7 \), meaning \( 7 - x = -(x - 7) \).
03
Substitute the negative to simplify
Replace \( 7 - x \) in the denominator with \( -(x - 7) \) to get the equivalent expression: \[ \frac{x - 7}{-(x - 7)} \].
04
Simplify the fraction
Now that both the numerator and denominator are \( x - 7 \), we can cancel these terms, remembering the negative sign in the denominator. This results in \( -1 \).
05
Write the final simplified expression
The expression is simplified to \( -1 \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Fractions
Fractions are a fundamental concept in algebra and mathematics as a whole. They represent a part of a whole and are expressed as a division of two numbers, with a numerator and a denominator. In our example, we have the fraction \( \frac{x-7}{7-x} \). Here, the numerator is \( x - 7 \), and the denominator is \( 7 - x \). Understanding fractions involves knowing how to manipulate them in operations like addition, subtraction, multiplication, and division.
- The numerator refers to the top part of the fraction.
- The denominator is the bottom part and tells us how many parts make up a whole.
Negatives in Algebra
Handling negatives in algebra correctly is crucial, as they can drastically change the meaning of an expression. When working with the expression \( \frac{x-7}{7-x} \), it is important to recognize the role of negatives. Here, the denominator \( 7 - x \) is actually \( -(x - 7) \). This is because the terms are reversed and can be factored by a negative sign.
- Negatives can flip the sign of a number or expression, which is why \( 7 - x \) equals \( -(x - 7) \).
- Recognizing these transformations helps in simplifying expressions more efficiently.
Canceling Terms
Canceling terms is a key skill in simplifying algebraic expressions, especially when dealing with fractions. In our given expression, after recognizing that \( 7-x \) is \( -(x-7) \), you rewrite the expression to show this negative equivalence: \( \frac{x-7}{-(x-7)} \).
- Canceling involves removing identical terms from both numerator and denominator.
- Ensure any terms you cancel have been properly factored or are identical with only numerical constants differentiating them.