The domain of the function [tex]\( f(x) \)[/tex] is [tex]\([-20, 15]\)[/tex] and the range is [tex]\((-\infty, 5]\)[/tex]. Using interval notation, find the domain and range of [tex]\( g(x) = 2 f(5x) + 1 \)[/tex].

Domain: [tex]\(\square\)[/tex]
Range: [tex]\(\square\)[/tex]



Answer :

Let's start by understanding how the transformations will affect the domain and range of the function [tex]\( g(x) = 2f(5x) + 1 \)[/tex].

### Domain Transformation

1. Original Domain of [tex]\( f(x) \)[/tex]:
[tex]\[ [-20, 15] \][/tex]

2. Adjusting for the inner function [tex]\( 5x \)[/tex] in [tex]\( f(5x) \)[/tex]:
[tex]\[ 5x \text{ must lie within } [-20, 15] \][/tex]

3. Solving for [tex]\( x \)[/tex] to find the new domain:
[tex]\[ -20 \leq 5x \leq 15 \][/tex]
[tex]\[ \frac{-20}{5} \leq x \leq \frac{15}{5} \][/tex]
[tex]\[ -4 \leq x \leq 3 \][/tex]

4. Thus, the domain of [tex]\( g(x) \)[/tex] is:
[tex]\[ [-4, 3] \][/tex]

### Range Transformation

1. Original Range of [tex]\( f(x) \)[/tex]:
[tex]\[ (-\infty, 5] \][/tex]

2. Transforming [tex]\( f(x) \)[/tex] to [tex]\( 2f(5x) \)[/tex]:
- The multiplication by 2 scales the range by a factor of 2.
- Therefore, the new range is:
[tex]\[ 2 \cdot (-\infty, 5] = (-\infty, 10] \][/tex]

3. Addition of 1 in [tex]\( 2f(5x) + 1 \)[/tex]:
- Adding 1 shifts the entire range up by 1 unit.
- Therefore, the range now becomes:
[tex]\[ (-\infty, 10] + 1 = (-\infty, 11] \][/tex]

4. Thus, the range of [tex]\( g(x) \)[/tex] is:
[tex]\[ (-\infty, 11] \][/tex]

### Final Answer
- Domain: [tex]\(\boxed{[-4, 3]}\)[/tex]
- Range: [tex]\(\boxed{(-\infty, 11]}\)[/tex]