The domain of the function [tex]$f(x)$[/tex] is [tex$[-1, 4]$[/tex] and the range is [tex[tex]$[6, 7]$[/tex][/tex]. Using interval notation, find the domain and range of [tex$g(x) = -f\left(\frac{1}{4}(x+5)\right)$[/tex].

Domain: [tex[tex]$\square$[/tex][/tex]

Range: [tex$\square$[/tex]



Answer :

To determine the domain and range of the function [tex]\( g(x) = -f\left(\frac{1}{4}(x + 5)\right) \)[/tex], given that the domain of [tex]\( f(x) \)[/tex] is [tex]\([-1,4]\)[/tex] and the range is [tex]\([6,7]\)[/tex], we need to follow a series of transformations.

### Step-by-Step Solution:

#### 1. Finding the Domain of [tex]\( g(x) \)[/tex]

The domain of [tex]\( g(x) \)[/tex] is determined by the expression inside the function [tex]\( f \)[/tex], i.e., [tex]\( \frac{1}{4}(x + 5) \)[/tex]. We need this expression to fall within the original domain of [tex]\( f \)[/tex], which is [tex]\([-1, 4]\)[/tex].

So we set up the inequality:

[tex]\[ -1 \leq \frac{1}{4}(x + 5) \leq 4 \][/tex]

Next, solve these inequalities for [tex]\( x \)[/tex]:

First inequality:
[tex]\[ -1 \leq \frac{1}{4}(x + 5) \][/tex]

Multiply both sides by 4:
[tex]\[ -4 \leq x + 5 \][/tex]

Subtract 5 from both sides:
[tex]\[ x \geq -9 \][/tex]

Second inequality:
[tex]\[ \frac{1}{4}(x + 5) \leq 4 \][/tex]

Multiply both sides by 4:
[tex]\[ x + 5 \leq 16 \][/tex]

Subtract 5 from both sides:
[tex]\[ x \leq 11 \][/tex]

So, the domain of [tex]\( g(x) \)[/tex] is:
[tex]\[ [-9, 11] \][/tex]

#### 2. Finding the Range of [tex]\( g(x) \)[/tex]

To determine the range of [tex]\( g(x) \)[/tex], we start with the given range of [tex]\( f(x) \)[/tex], which is [tex]\([6, 7]\)[/tex].

Since [tex]\( g(x) = -f\left(\frac{1}{4}(x + 5)\right) \)[/tex], we are applying a vertical reflection (multiplying by -1).

To find the new range, we multiply the values of the range of [tex]\( f(x) \)[/tex] by -1:
- The maximum value in the range of [tex]\( f(x) \)[/tex] will become the minimum value in the range of [tex]\( g(x) \)[/tex].
- The minimum value in the range of [tex]\( f(x) \)[/tex] will become the maximum value in the range of [tex]\( g(x) \)[/tex].

Original range of [tex]\( f(x) \)[/tex]:
[tex]\[ [6, 7] \][/tex]

After multiplying by -1:
[tex]\[ -7 \text{ (from 6)}, -6 \text{ (from 7)} \][/tex]

So, the range of [tex]\( g(x) \)[/tex] is:
[tex]\[ [-7, -6] \][/tex]

### Final Result:

Domain: [tex]\([-9, 11]\)[/tex]

Range: [tex]\([-7, -6]\)[/tex]

Therefore, the final answer in interval notation is:
[tex]\[ \text{Domain: } [-9, 11] \quad \text{Range: } [-7, -6] \][/tex]