Math Problem Statement

Find the domain and range of 1/root(25-x²)

Solution

To find the domain and range of the function f(x)=125x2f(x) = \frac{1}{\sqrt{25 - x^2}}, we need to ensure that the expression inside the square root is non-negative, and that the denominator is non-zero.

1. Domain:

The function is defined when:

  • The expression inside the square root, 25x225 - x^2, is non-negative, meaning 25x2025 - x^2 \geq 0.
  • The denominator must not be zero, so 25x20\sqrt{25 - x^2} \neq 0.

Let's solve these conditions step by step.

Step 1: Solve 25x2025 - x^2 \geq 0:

25x2    5x525 \geq x^2 \implies -5 \leq x \leq 5 This gives the interval x[5,5]x \in [-5, 5], which ensures the square root is non-negative.

Step 2: Ensure the denominator is non-zero:

For the denominator to be non-zero, 25x20\sqrt{25 - x^2} \neq 0, which means 25x2025 - x^2 \neq 0. This simplifies to: x225    x±5x^2 \neq 25 \implies x \neq \pm 5

Thus, the domain is all xx such that 5<x<5-5 < x < 5.

Final Domain:

x(5,5)x \in (-5, 5)

2. Range:

To find the range of f(x)=125x2f(x) = \frac{1}{\sqrt{25 - x^2}}, we need to consider the behavior of the function within its domain.

  • As xx approaches 5-5 or 55, the term 25x2\sqrt{25 - x^2} approaches zero, meaning f(x)f(x) approaches infinity.
  • As xx approaches 0, 2502=25=5\sqrt{25 - 0^2} = \sqrt{25} = 5, so f(0)=15f(0) = \frac{1}{5}.

Thus, the function can take any value from 15\frac{1}{5} to ++\infty.

Final Range:

f(x)(15,+)f(x) \in \left( \frac{1}{5}, +\infty \right)

Summary:

  • Domain: (5,5)(-5, 5)
  • Range: (15,+)\left( \frac{1}{5}, +\infty \right)

Would you like more details or have any questions? Here are some related questions:

  1. How do we handle square roots in other types of functions?
  2. What happens when xx is exactly 5 or -5?
  3. How do we find the range of a rational function in general?
  4. What transformations would shift the domain and range of this function?
  5. How would the domain and range change if the square root expression were 25x425 - x^4?

Tip: Always check both the non-negativity of square roots and the non-zero condition for denominators when dealing with such functions.

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Math Problem Analysis

Mathematical Concepts

Domain and Range
Inequalities
Square Root Functions

Formulas

25 - x² ≥ 0 (for the square root to be defined)
√(25 - x²) ≠ 0 (denominator must not be zero)
Range determined by behavior as x approaches domain limits

Theorems

Square root must be non-negative
Denominator must not be zero in rational functions

Suitable Grade Level

Grades 10-12