Math Problem Statement

Divide as indicated: (x^2 - 49) / x divided by (x + 7) / (x - 7). Simplify the expression and determine if any values of x must be excluded.

Solution

The problem asks to divide two rational expressions and select the correct simplification, with attention to any excluded values for xx.

Step 1: Simplify the Expression

The given expression is:

x249xx+7x7\frac{\frac{x^2 - 49}{x}}{\frac{x + 7}{x - 7}}

This can be rewritten as a multiplication by taking the reciprocal of the denominator:

x249x×x7x+7\frac{x^2 - 49}{x} \times \frac{x - 7}{x + 7}

Step 2: Factor the Numerator x249x^2 - 49

We recognize that x249x^2 - 49 is a difference of squares:

x249=(x7)(x+7)x^2 - 49 = (x - 7)(x + 7)

Step 3: Substitute the Factored Form

Substituting the factored form of x249x^2 - 49 into the expression:

(x7)(x+7)x×x7x+7\frac{(x - 7)(x + 7)}{x} \times \frac{x - 7}{x + 7}

Step 4: Cancel Common Factors

Now we can cancel out the common factors (x+7)(x + 7) from the numerator and denominator:

(x7)x×(x7)=(x7)2x\frac{(x - 7)}{x} \times (x - 7) = \frac{(x - 7)^2}{x}

Step 5: Determine Excluded Values

The denominator of the original expression contains xx and x7x - 7, so we must exclude values of xx that make the denominator zero. These values are:

  • x0x \neq 0 (from the term 1x\frac{1}{x})
  • x7x \neq 7 (from the term 1x7\frac{1}{x - 7})

Final Answer

The simplified expression is:

(x7)2x,x0,7\frac{(x - 7)^2}{x}, \quad x \neq 0, 7

Correct Choice

The correct answer is Option A, with the conditions x0x \neq 0 and x7x \neq 7.


Would you like more details or have any questions? Here are 5 related questions to expand your understanding:

  1. How do you factor other quadratic expressions, such as x2+bx+cx^2 + bx + c?
  2. What are the steps to simplify more complex rational expressions?
  3. How do you handle rational expressions with multiple variables?
  4. What happens when you divide polynomials with more complicated denominators?
  5. How do you find excluded values in rational expressions involving roots?

Tip: Always check for excluded values by setting each denominator in the expression equal to zero and solving for the variable.

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Math Problem Analysis

Mathematical Concepts

Algebra
Rational Expressions
Factoring
Difference of Squares

Formulas

(a^2 - b^2) = (a - b)(a + b)
Simplification of rational expressions

Theorems

Difference of Squares Theorem
Simplification of Rational Expressions Theorem

Suitable Grade Level

Grades 9-12