Given [tex]\( h(x) = 3 \sqrt{x+2} \)[/tex], which of the following statements describes [tex]\( h(x) \)[/tex]?

A. The function [tex]\( h(x) \)[/tex] is increasing on the interval [tex]\( (-\infty, -2) \)[/tex].

B. The function [tex]\( h(x) \)[/tex] is decreasing on the interval [tex]\( (2, \infty) \)[/tex].

C. The function [tex]\( h(x) \)[/tex] is decreasing on the interval [tex]\( (-\infty, 2) \)[/tex].

D. The function [tex]\( h(x) \)[/tex] is increasing on the interval [tex]\( (-2, \infty) \)[/tex].



Answer :

Let's examine the function [tex]\( h(x) = 3\sqrt{x+2} \)[/tex] to determine its behavior.

1. Find the derivative [tex]\(h'(x)\)[/tex]:

To determine where the function is increasing or decreasing, we need to find the first derivative of [tex]\( h(x) \)[/tex].

[tex]\[ h(x) = 3\sqrt{x+2} \][/tex]

To find the derivative, we use the chain rule. Recall that the derivative of [tex]\( \sqrt{u} \)[/tex] with respect to [tex]\( u \)[/tex] is [tex]\( \frac{1}{2\sqrt{u}} \)[/tex], and let [tex]\( u = x + 2 \)[/tex].

[tex]\[ h'(x) = 3 \cdot \frac{1}{2\sqrt{x+2}} \cdot (1) = \frac{3}{2\sqrt{x+2}} \][/tex]

2. Simplified first derivative:

The simplified first derivative is:

[tex]\[ h'(x) = \frac{3}{2\sqrt{x+2}} \][/tex]

3. Determine where the function is increasing:

The function [tex]\( h(x) \)[/tex] will be increasing where [tex]\( h'(x) > 0 \)[/tex].

[tex]\[ \frac{3}{2\sqrt{x+2}} > 0 \][/tex]

Since the square root function [tex]\(\sqrt{x+2}\)[/tex] is always positive for [tex]\( x > -2 \)[/tex], [tex]\(h'(x)\)[/tex] is also always positive for [tex]\( x > -2 \)[/tex].

4. Domain of [tex]\( h(x) \)[/tex]:

The domain of [tex]\( h(x) \)[/tex] is determined by the requirement that the expression under the square root must be non-negative:

[tex]\[ x + 2 \geq 0 \implies x \geq -2 \][/tex]

5. Conclusion on intervals where [tex]\( h(x) \)[/tex] is increasing:

Because [tex]\( h'(x) \)[/tex] is always positive for [tex]\( x > -2 \)[/tex], the function [tex]\( h(x) \)[/tex] is increasing on its domain [tex]\( (-2, \infty) \)[/tex].

Therefore, the correct statement describing [tex]\( h(x) = 3\sqrt{x+2} \)[/tex] is:

- The function [tex]\( h(x) \)[/tex] is increasing on the interval [tex]\( (-2, \infty) \)[/tex].