Which statement is true about the function [tex]$f(x)=\sqrt{-x}$[/tex]?

A. It has the same domain as the function [tex]$f(x)=-\sqrt{-x}$[/tex].
B. It has the same range as the function [tex][tex]$f(x)=-\sqrt{-x}$[/tex][/tex].
C. It has the same domain as the function [tex]$f(x)=-\sqrt{x}$[/tex].
D. It has the same range as the function [tex]$f(x)=-\sqrt{x}$[/tex].



Answer :

Sure, let's analyze the function [tex]\( f(x) = \sqrt{-x} \)[/tex] along with other functions given in the options to determine the correct statement.

### 1. Domain and Range of [tex]\( f(x) = \sqrt{-x} \)[/tex]

- Domain: The expression inside the square root, [tex]\(-x\)[/tex], must be non-negative for [tex]\( \sqrt{-x} \)[/tex] to be defined.
- This means [tex]\( -x \geq 0 \)[/tex] or [tex]\( x \leq 0 \)[/tex].
- Domain: [tex]\( (-\infty, 0] \)[/tex]

- Range: The square root of a non-negative number is non-negative.
- So, [tex]\( \sqrt{-x} \)[/tex] produces non-negative results.
- Range: [tex]\( [0, \infty) \)[/tex]

### 2. Domain and Range of [tex]\( f(x) = -\sqrt{-x} \)[/tex]

- Domain: The condition on the domain remains the same as for [tex]\( \sqrt{-x} \)[/tex].
- [tex]\( -x \geq 0 \)[/tex] or [tex]\( x \leq 0 \)[/tex].
- Domain: [tex]\( (-\infty, 0] \)[/tex]

- Range: Multiplying the square root function by -1 makes the non-negative results into non-positive results.
- So, [tex]\( -\sqrt{-x} \)[/tex] produces non-positive results.
- Range: [tex]\( (-\infty, 0] \)[/tex]

### 3. Domain and Range of [tex]\( f(x) = -\sqrt{x} \)[/tex]

- Domain: The expression inside the square root, [tex]\(x\)[/tex], must be non-negative.
- [tex]\( x \geq 0 \)[/tex]
- Domain: [tex]\( [0, \infty) \)[/tex]

- Range: Multiplying the square root function by -1 changes the non-negative results to non-positive results.
- So, [tex]\( -\sqrt{x} \)[/tex] produces non-positive results.
- Range: [tex]\( (-\infty, 0] \)[/tex]

### Summary of Findings

1. The function [tex]\( f(x) = \sqrt{-x} \)[/tex] has the same domain as the function [tex]\( f(x) = -\sqrt{-x} \)[/tex].
- Both domains: [tex]\( (-\infty, 0] \)[/tex]

2. The function [tex]\( f(x) = \sqrt{-x} \)[/tex] does not have the same range as the function [tex]\( f(x) = -\sqrt{-x} \)[/tex].
- [tex]\( \sqrt{-x} \)[/tex]: Range [tex]\( [0, \infty) \)[/tex]
- [tex]\( -\sqrt{-x} \)[/tex]: Range [tex]\( (-\infty, 0] \)[/tex]

3. The function [tex]\( f(x) = \sqrt{-x} \)[/tex] does not have the same domain as the function [tex]\( f(x) = -\sqrt{x} \)[/tex].
- [tex]\( \sqrt{-x} \)[/tex]: Domain [tex]\( (-\infty, 0] \)[/tex]
- [tex]\( -\sqrt{x} \)[/tex]: Domain [tex]\( [0, \infty) \)[/tex]

4. The function [tex]\( f(x) = \sqrt{-x} \)[/tex] does not have the same range as the function [tex]\( f(x) = -\sqrt{x} \)[/tex].
- [tex]\( \sqrt{-x} \)[/tex]: Range [tex]\( [0, \infty) \)[/tex]
- [tex]\( -\sqrt{x} \)[/tex]: Range [tex]\( (-\infty, 0] \)[/tex]

Based on this detailed analysis, the true statement is:

The function [tex]\( f(x) = \sqrt{-x} \)[/tex] has the same domain as the function [tex]\( f(x) = -\sqrt{-x} \)[/tex].