Math Problem Statement

Given the functions f(x) = -2x, g(x) = |x + 7|, and h(x) = 1 / (x - 5), evaluate the function (h / f)(-5).

Solution

We are given three functions:

  • f(x)=2xf(x) = -2x
  • g(x)=x+7g(x) = |x + 7|
  • h(x)=1x5h(x) = \frac{1}{x - 5}

We are asked to evaluate (hf)(5)\left( \frac{h}{f} \right)(-5), meaning we need to compute h(5)f(5)\frac{h(-5)}{f(-5)}.

Step 1: Evaluate h(5)h(-5)

The function h(x)=1x5h(x) = \frac{1}{x - 5}.

For x=5x = -5: h(5)=155=110=110h(-5) = \frac{1}{-5 - 5} = \frac{1}{-10} = -\frac{1}{10}

Step 2: Evaluate f(5)f(-5)

The function f(x)=2xf(x) = -2x.

For x=5x = -5: f(5)=2(5)=10f(-5) = -2(-5) = 10

Step 3: Compute h(5)f(5)\frac{h(-5)}{f(-5)}

h(5)f(5)=11010=110×110=1100\frac{h(-5)}{f(-5)} = \frac{-\frac{1}{10}}{10} = -\frac{1}{10} \times \frac{1}{10} = -\frac{1}{100}

Thus, the value of (hf)(5)\left( \frac{h}{f} \right)(-5) is 1100-\frac{1}{100}.

Do you need further clarification or additional details?


Here are five related questions for practice:

  1. How would you evaluate (gf)(5)\left( \frac{g}{f} \right)(-5)?
  2. What is the domain of the function h(x)=1x5h(x) = \frac{1}{x - 5}?
  3. How do you compute (hg)(5)\left( \frac{h}{g} \right)(-5)?
  4. What is the value of g(5)g(-5) for g(x)=x+7g(x) = |x + 7|?
  5. How would you simplify the expression 110×110\frac{1}{10} \times \frac{1}{10}?

Tip:

When dividing fractions, remember to multiply by the reciprocal of the denominator!

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Math Problem Analysis

Mathematical Concepts

Functions
Division of Functions
Substitution

Formulas

f(x) = -2x
g(x) = |x + 7|
h(x) = 1 / (x - 5)
Division of functions: (h / f)(x) = h(x) / f(x)

Theorems

Basic Function Substitution

Suitable Grade Level

Grades 9-12