2. Determine whether these are well-defined functions. Explain. 3 (a) f:R → R, where f(x) = 2² + 5° 7 (b) g: (5, 0) → R, where g(x) = Vx – 4 (c) h:R → R, where h(x) = -V7 – 4x + 4x².

Advanced Engineering Mathematics
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Chapter2: Second-order Linear Odes
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### Function Analysis: Well-Defined Criteria

Let's determine whether the given functions are well-defined, considering their domains and any restrictions imposed by their expressions.

#### (a) Function \( f: \mathbb{R} \to \mathbb{R} \)

- **Definition:** \( f(x) = \frac{3}{x^2 + 5} \)
- **Domain:** The function is defined for all real numbers \( x \) because the denominator \( x^2 + 5 \) is always positive and never zero (since \( x^2 \geq 0 \) implies \( x^2 + 5 \geq 5 \)).
- **Conclusion:** The function \( f(x) \) is well-defined over the entire set of real numbers.

#### (b) Function \( g: (5, \infty) \to \mathbb{R} \)

- **Definition:** \( g(x) = \frac{7}{\sqrt{x - 4}} \)
- **Domain:** The expression \( \sqrt{x - 4} \) implies \( x - 4 > 0 \), so \( x > 4 \). Thus, the domain is properly set as \( (5, \infty) \) because each \( x \) in this interval satisfies \( x > 4 \).
- **Conclusion:** The function \( g(x) \) is well-defined on \( (5, \infty) \).

#### (c) Function \( h: \mathbb{R} \to \mathbb{R} \)

- **Definition:** \( h(x) = -\sqrt{7 - 4x + 4x^2} \)
- **Domain:** The expression inside the square root \( 7 - 4x + 4x^2 \) must be non-negative for \( h(x) \) to be defined. Calculating the discriminant of the quadratic \( 4x^2 - 4x + 7 \) shows that it doesn't have real roots, and therefore, it is always positive.
- **Conclusion:** The function \( h(x) \) is well-defined for all real numbers.

Each function meets the criteria for being well-defined within its specified domain.
Transcribed Image Text:### Function Analysis: Well-Defined Criteria Let's determine whether the given functions are well-defined, considering their domains and any restrictions imposed by their expressions. #### (a) Function \( f: \mathbb{R} \to \mathbb{R} \) - **Definition:** \( f(x) = \frac{3}{x^2 + 5} \) - **Domain:** The function is defined for all real numbers \( x \) because the denominator \( x^2 + 5 \) is always positive and never zero (since \( x^2 \geq 0 \) implies \( x^2 + 5 \geq 5 \)). - **Conclusion:** The function \( f(x) \) is well-defined over the entire set of real numbers. #### (b) Function \( g: (5, \infty) \to \mathbb{R} \) - **Definition:** \( g(x) = \frac{7}{\sqrt{x - 4}} \) - **Domain:** The expression \( \sqrt{x - 4} \) implies \( x - 4 > 0 \), so \( x > 4 \). Thus, the domain is properly set as \( (5, \infty) \) because each \( x \) in this interval satisfies \( x > 4 \). - **Conclusion:** The function \( g(x) \) is well-defined on \( (5, \infty) \). #### (c) Function \( h: \mathbb{R} \to \mathbb{R} \) - **Definition:** \( h(x) = -\sqrt{7 - 4x + 4x^2} \) - **Domain:** The expression inside the square root \( 7 - 4x + 4x^2 \) must be non-negative for \( h(x) \) to be defined. Calculating the discriminant of the quadratic \( 4x^2 - 4x + 7 \) shows that it doesn't have real roots, and therefore, it is always positive. - **Conclusion:** The function \( h(x) \) is well-defined for all real numbers. Each function meets the criteria for being well-defined within its specified domain.
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