Math Problem Statement

find the domain, range, and all zeros/intercepts, if any, of the functions, 3/x-4

Solution

Let's analyze the function f(x)=3x4f(x) = \frac{3}{x - 4}.

1. Domain:

The domain of a function consists of all the values of xx for which the function is defined. The function f(x)=3x4f(x) = \frac{3}{x - 4} is undefined where the denominator equals zero.

Set the denominator equal to zero and solve for xx:

x4=0x - 4 = 0

x=4x = 4

So, the function is undefined at x=4x = 4. Thus, the domain of f(x)f(x) is:

Domain: (,4)(4,)\text{Domain: } (-\infty, 4) \cup (4, \infty)

2. Range:

The range of a function consists of all possible values of f(x)f(x). For the function f(x)=3x4f(x) = \frac{3}{x - 4}, since it is a rational function where the numerator is a constant (3) and the denominator can take any real value (except zero), the function can approach any real number except zero.

Thus, the range is:

Range: (,0)(0,)\text{Range: } (-\infty, 0) \cup (0, \infty)

3. Zeros/Intercepts:

To find the zeros of the function, we set f(x)=0f(x) = 0 and solve for xx:

3x4=0\frac{3}{x - 4} = 0

However, a fraction equals zero only when the numerator is zero. Here, the numerator is 3, which is never zero. Therefore, there are no zeros (or x-intercepts) for this function.

Y-Intercept:

To find the y-intercept, we evaluate f(x)f(x) at x=0x = 0:

f(0)=304=34=34f(0) = \frac{3}{0 - 4} = \frac{3}{-4} = -\frac{3}{4}

Thus, the y-intercept is:

Y-Intercept: (0,34)\text{Y-Intercept: } \left(0, -\frac{3}{4}\right)

Summary:

  • Domain: (,4)(4,)(-\infty, 4) \cup (4, \infty)
  • Range: (,0)(0,)(-\infty, 0) \cup (0, \infty)
  • Zeros/Intercepts:
    • No zeros (x-intercepts)
    • Y-intercept at (0,34)\left(0, -\frac{3}{4}\right)

Would you like further details or have any questions?


Here are five related questions:

  1. How do you determine the domain of a more complex rational function?
  2. What happens to the graph of f(x)=3x4f(x) = \frac{3}{x-4} near the point where the function is undefined?
  3. How would the domain and range change if the function was f(x)=3x4+2f(x) = \frac{3}{x-4} + 2?
  4. Can a rational function have more than one y-intercept? Why or why not?
  5. What are asymptotes, and how do they relate to the function f(x)=3x4f(x) = \frac{3}{x-4}?

Tip: When finding the domain of a function, always look out for values that make the denominator zero or cause other undefined operations like square roots of negative numbers.

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Math Problem Analysis

Mathematical Concepts

Functions
Rational Functions

Formulas

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Theorems

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Suitable Grade Level

Grades 11-12