Math Problem Statement

What is the domain of \( \frac{f}{g}(x) = \frac{x+7}{x+3} \)?

Solution

The function in question is fg(x)=x+7x+3\frac{f}{g}(x) = \frac{x+7}{x+3}, and the task is to determine the domain of this function.

Step-by-step explanation:

  1. Identify restrictions on the domain: The domain of fg(x)\frac{f}{g}(x) is all real numbers except where the denominator equals zero. The denominator is x+3x + 3, so we set it equal to zero: x+3=0    x=3.x + 3 = 0 \implies x = -3. Therefore, x=3x = -3 is excluded from the domain.

  2. Examine the given domain interval: The problem asks for the domain in the interval (3,)(-3, \infty). However, the domain of fg(x)\frac{f}{g}(x) will also be restricted at any other points where the denominator makes the function undefined.

  3. Check for discontinuities in the numerator: The numerator x+7x+7 is a linear function and does not impose any additional restrictions on the domain, as it is defined for all real numbers.

Conclusion:

The only restriction on the domain is x=3x = -3. Hence, the correct domain of fg(x)\frac{f}{g}(x) is: (,3)(3,).(-\infty, -3) \cup (-3, \infty).

Verification:

  • Choice A corresponds to the domain (7,3)(3,)(-7, -3) \cup (-3, \infty), which seems to contain a mistake because the lower bound should extend to -\infty, not 7-7.
  • Choice B represents the empty set, which is incorrect.
  • Choice C also represents an empty set, which is incorrect.

So, the correct domain should actually be (,3)(3,)(-\infty, -3) \cup (-3, \infty), but this choice is not given in the options.

Would you like further details or clarifications?


Here are 5 related questions:

  1. What are the steps to find the domain of a rational function in general?
  2. How does the numerator of a fraction affect the domain of the function?
  3. Why does division by zero make a function undefined?
  4. Can the function fg(x)\frac{f}{g}(x) have a domain that is smaller than the domain of either f(x)f(x) or g(x)g(x) alone?
  5. How would the domain change if the denominator were x2+3xx^2 + 3x instead of x+3x + 3?

Tip: Always check both the numerator and denominator for restrictions when finding the domain of a rational function.

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Math Problem Analysis

Mathematical Concepts

Rational Functions
Domain Restrictions

Formulas

The function is undefined where the denominator is zero, so solve \( x+3 = 0 \) to find the excluded value.

Theorems

A function is undefined when its denominator equals zero.

Suitable Grade Level

Grades 9-12