Math Problem Statement

Find the domain and range of the inverse of f(x) = x²-6x+5 with domain restriction (x ∈ R 0 < x <3}.

Solution

To find the domain and range of the inverse of the function f(x)=x26x+5f(x) = x^2 - 6x + 5 with the domain restriction 0<x<30 < x < 3, we can follow these steps:

1. Determine the range of the given function f(x)f(x):

  • The function is a quadratic equation of the form f(x)=ax2+bx+cf(x) = ax^2 + bx + c, where a=1a = 1, b=6b = -6, and c=5c = 5.

  • First, complete the square to express the function in vertex form.

    f(x)=x26x+5f(x) = x^2 - 6x + 5

    To complete the square:

    f(x)=(x26x+9)9+5=(x3)24f(x) = (x^2 - 6x + 9) - 9 + 5 = (x - 3)^2 - 4

    So,

    f(x)=(x3)24f(x) = (x - 3)^2 - 4

  • The vertex of the parabola is at x=3x = 3, y=4y = -4. Since the parabola opens upwards and the domain restriction is 0<x<30 < x < 3, the range of f(x)f(x) when 0<x<30 < x < 3 corresponds to 4<f(x)<5-4 < f(x) < 5.

2. Find the inverse function f1(x)f^{-1}(x):

  • To find the inverse, first, solve for xx in terms of yy:

    y=(x3)24y = (x - 3)^2 - 4

    Add 4 to both sides:

    y+4=(x3)2y + 4 = (x - 3)^2

    Take the square root of both sides:

    y+4=x3\sqrt{y + 4} = x - 3

    Therefore,

    x=y+4+3x = \sqrt{y + 4} + 3

    The inverse function is:

    f1(x)=x+4+3f^{-1}(x) = \sqrt{x + 4} + 3

3. Determine the domain and range of the inverse function f1(x)f^{-1}(x):

  • Domain of f1(x)f^{-1}(x): The domain of the inverse function is the range of the original function. Since the range of f(x)f(x) was 4<f(x)<5-4 < f(x) < 5, the domain of f1(x)f^{-1}(x) is 4<x<5-4 < x < 5.
  • Range of f1(x)f^{-1}(x): The range of the inverse function corresponds to the original domain 0<x<30 < x < 3. So, the range of f1(x)f^{-1}(x) is 3<f1(x)<53 < f^{-1}(x) < 5.

Final Answer:

  • Domain of f1(x)f^{-1}(x): 4<x<5-4 < x < 5
  • Range of f1(x)f^{-1}(x): 3<y<53 < y < 5

Would you like more details on any part of this solution?


Related Questions:

  1. How would the inverse function change if the domain restriction was x3x \geq 3?
  2. Can you explain how to graph the function f(x)=x26x+5f(x) = x^2 - 6x + 5 and its inverse?
  3. What would be the domain and range of f1(x)f^{-1}(x) if the original function had no domain restriction?
  4. How do you find the inverse of a function that isn't one-to-one?
  5. What is the significance of completing the square in finding the inverse of a quadratic function?

Tip: When dealing with quadratic functions, completing the square is a powerful technique for identifying key features like the vertex, which aids in finding the inverse.

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Math Problem Analysis

Mathematical Concepts

Functions
Quadratic Equations
Inverse Functions

Formulas

Quadratic equation
Inverse function formula

Theorems

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Suitable Grade Level

Grades 10-12