Math Problem Statement

Confirm that f and g are inverses by showing that

​f(g(x))equals=x

and

​g(f(x))equals=x.

​f(x)equals=StartFraction x minus 4 Over x EndFractionx−4x​,

​g(x)equals=negative StartFraction 4 Over x minus 1 EndFraction−4x−1

Question content area bottom

Part 1

Is​ f(g(x)) equal to​ x?

Yes

No

Part 2

Is​ g(f(x)) equal to​ x?

No

Yes

Solution

To confirm that two functions f(x)f(x) and g(x)g(x) are inverses of each other, we need to show that both of the following are true:

  1. f(g(x))=xf(g(x)) = x
  2. g(f(x))=xg(f(x)) = x

We will go step by step to verify both conditions.

Given Functions:

  • f(x)=x4xf(x) = \frac{x - 4}{x}
  • g(x)=4x1g(x) = -\frac{4}{x - 1}

Part 1: Is f(g(x))=xf(g(x)) = x?

We substitute g(x)g(x) into f(x)f(x):

f(g(x))=f(4x1)=(4x1)4(4x1)f(g(x)) = f\left(-\frac{4}{x - 1}\right) = \frac{\left(-\frac{4}{x - 1}\right) - 4}{\left(-\frac{4}{x - 1}\right)}

Simplify the numerator:

(4x1)4=44(x1)x1=44x+4x1=4xx1\left(-\frac{4}{x - 1}\right) - 4 = \frac{-4 - 4(x - 1)}{x - 1} = \frac{-4 - 4x + 4}{x - 1} = \frac{-4x}{x - 1}

Now, substitute this into the expression for f(g(x))f(g(x)):

f(g(x))=4xx14x1=xf(g(x)) = \frac{\frac{-4x}{x - 1}}{-\frac{4}{x - 1}} = x

So, f(g(x))=xf(g(x)) = x. The answer for Part 1 is Yes.

Part 2: Is g(f(x))=xg(f(x)) = x?

We substitute f(x)f(x) into g(x)g(x):

g(f(x))=g(x4x)=4x4x1g(f(x)) = g\left(\frac{x - 4}{x}\right) = -\frac{4}{\frac{x - 4}{x} - 1}

Simplify the denominator:

x4x1=x4xx=4x\frac{x - 4}{x} - 1 = \frac{x - 4 - x}{x} = \frac{-4}{x}

Now substitute this back into g(f(x))g(f(x)):

g(f(x))=44x=xg(f(x)) = -\frac{4}{\frac{-4}{x}} = x

So, g(f(x))=xg(f(x)) = x. The answer for Part 2 is Yes.

Final Answer:

  • Part 1: Yes
  • Part 2: Yes

Both functions are indeed inverses of each other.

Would you like more details or have any questions?

Here are 5 related questions to explore further:

  1. What are the general properties of inverse functions?
  2. How can we algebraically find the inverse of a given function?
  3. What is the geometric relationship between a function and its inverse on a graph?
  4. How can we verify that a function is one-to-one before finding its inverse?
  5. How does the domain and range of a function relate to the domain and range of its inverse?

Tip: Always check that the composition of a function with its inverse gives back the identity function, xx, to verify they are truly inverses.

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Math Problem Analysis

Mathematical Concepts

Algebra
Inverse Functions
Function Composition

Formulas

f(g(x)) = f(-4/(x - 1)) = ((-4/(x - 1)) - 4)/(-4/(x - 1)) = x
g(f(x)) = g((x - 4)/x) = -4/(((x - 4)/x) - 1) = x

Theorems

Inverse Function Theorem
Function Composition

Suitable Grade Level

Grades 10-12