Given the function [tex]$h(x) = -5 \sqrt{x}$[/tex], which statement is true about [tex]$h(x)$[/tex]?

A. The function is decreasing on the interval [tex]$(-\infty, 0)$[/tex].
B. The function is increasing on the interval [tex][tex]$(-\infty, 0)$[/tex][/tex].
C. The function is decreasing on the interval [tex]$(0, \infty)$[/tex].
D. The function is increasing on the interval [tex]$(0, \infty)$[/tex].



Answer :

To determine the behavior of the function [tex]\( h(x) = -5 \sqrt{x} \)[/tex], let’s analyze it step by step.

1. Domain of the Function:
The function [tex]\( \sqrt{x} \)[/tex] is only defined for [tex]\( x \geq 0 \)[/tex] because the square root of a negative number is not a real number. Therefore, the domain of [tex]\( h(x) = -5 \sqrt{x} \)[/tex] is [tex]\( x \geq 0 \)[/tex].

2. Behavior of the Square Root Function:
The fundamental parent function [tex]\( \sqrt{x} \)[/tex] is increasing on its entire domain [tex]\( x \geq 0 \)[/tex]. As [tex]\( x \)[/tex] increases, [tex]\( \sqrt{x} \)[/tex] also increases.

3. Effect of the Multiplication by -5:
Multiplying the square root function by a negative constant, in this case, -5, reverses its direction. Thus, instead of increasing, the function [tex]\( h(x) = -5 \sqrt{x} \)[/tex] will be decreasing on its domain. The negative sign indicates that as [tex]\( x \)[/tex] increases, [tex]\( -5 \sqrt{x} \)[/tex] decreases.

4. Interval Analysis:
Since [tex]\( h(x) = -5 \sqrt{x} \)[/tex] is defined for [tex]\( x \geq 0 \)[/tex], we need to consider the intervals within this domain. Analyzing the behavior of the function within the interval [tex]\( (0, \infty) \)[/tex]:
- As [tex]\( x \)[/tex] increases from 0 to [tex]\( \infty \)[/tex], [tex]\( \sqrt{x} \)[/tex] increases, but multiplying by -5 makes the entire expression [tex]\( -5 \sqrt{x} \)[/tex] decrease.

Therefore, we conclude that the function [tex]\( h(x) = -5 \sqrt{x} \)[/tex] is decreasing on the interval [tex]\( (0, \infty) \)[/tex].

Among the given statements, the correct one is:
- The function is decreasing on the interval [tex]\( (0, \infty) \)[/tex].