Which function has a range that includes -4?

[tex]\[
\begin{array}{l}
y=\sqrt{x}-5 \\
y=\sqrt{x}+5 \\
y=\sqrt{x+5} \\
y=\sqrt{x-5}
\end{array}
\][/tex]



Answer :

Let's systematically analyze each of the given functions to determine which one can have a range that includes [tex]\(-4\)[/tex].

1. Function: [tex]\( y = \sqrt{x} - 5 \)[/tex]

Let's see if it is possible for [tex]\( y = -4 \)[/tex]:
[tex]\[ -4 = \sqrt{x} - 5 \][/tex]
By adding 5 to both sides, we obtain:
[tex]\[ 1 = \sqrt{x} \][/tex]
Squaring both sides to eliminate the square root, we get:
[tex]\[ x = 1 \][/tex]
Since [tex]\( x = 1 \)[/tex] is a valid value (it's non-negative), [tex]\( y = \sqrt{x} - 5 \)[/tex] can indeed equal [tex]\(-4\)[/tex] when [tex]\( x = 1 \)[/tex].

Thus, the range of [tex]\( y = \sqrt{x} - 5 \)[/tex] includes [tex]\(-4\)[/tex].

2. Function: [tex]\( y = \sqrt{x} + 5 \)[/tex]

Similarly, we try to see if [tex]\( y = -4 \)[/tex] is possible:
[tex]\[ -4 = \sqrt{x} + 5 \][/tex]
Subtracting 5 from both sides, we find:
[tex]\[ -9 = \sqrt{x} \][/tex]
This result is impossible because the square root of [tex]\( x \)[/tex] (where [tex]\( x \geq 0 \)[/tex]) is always non-negative. Thus, [tex]\( y = \sqrt{x} + 5 \)[/tex] cannot have a value of [tex]\(-4\)[/tex].

3. Function: [tex]\( y = \sqrt{x+5} \)[/tex]

Check if [tex]\( y = -4 \)[/tex]:
[tex]\[ -4 = \sqrt{x+5} \][/tex]
Similar to the previous case, squaring both sides gives:
[tex]\[ 16 = x + 5 \][/tex]
Solving for [tex]\( x \)[/tex], we get:
[tex]\[ x = 16 - 5 = 11 \][/tex]
However, when we checked this previously, squaring gave an incorrect condition since square roots do not yield negative numbers.

In this particular circumstance, [tex]\( y = \sqrt{x+5} \)[/tex] cannot equal [tex]\(-4\)[/tex].

4. Function: [tex]\( y = \sqrt{x-5} \)[/tex]

Let's investigate if [tex]\( y = -4 \)[/tex]:
[tex]\[ -4 = \sqrt{x-5} \][/tex]
Squaring both sides results in:
[tex]\[ 16 = x - 5 \][/tex]
Solving for [tex]\( x \)[/tex], we get:
[tex]\[ x = 16 + 5 = 21 \][/tex]
Once again, this situation results from incorrectly calculating negative roots.

Therefore, [tex]\( y = \sqrt{x-5} \)[/tex] also cannot equal [tex]\(-4\)[/tex].

From this detailed examination, we conclude that the range of the function [tex]\( y = \sqrt{x} - 5 \)[/tex] includes [tex]\(-4\)[/tex].