Pablo generates the function [tex]f(x)=\frac{3}{2}\left(\frac{5}{2}\right)^{x-1}[/tex] to determine the [tex]x^{\text{th}}[/tex] number in a sequence.

Which is an equivalent representation?

A. [tex]f(x+1)=\frac{5}{2} f(x)[/tex]

B. [tex]f(x)=\frac{5}{2} f(x+1)[/tex]

C. [tex]f(x+1)=\frac{3}{2} f(x)[/tex]

D. [tex]f(x)=\frac{3}{2} f(x+1)[/tex]



Answer :

To determine which expression is an equivalent representation of the function [tex]\( f(x) = \frac{3}{2} \left( \frac{5}{2} \right)^{x-1} \)[/tex], let's examine and verify each given option step by step.

### Option 1: [tex]\( f(x+1) = \frac{5}{2} f(x) \)[/tex]

First, calculate [tex]\( f(x+1) \)[/tex]:
[tex]\[ f(x+1) = \frac{3}{2} \left( \frac{5}{2} \right)^{(x+1)-1} = \frac{3}{2} \left( \frac{5}{2} \right)^x \][/tex]

Now, calculate [tex]\( \frac{5}{2} f(x) \)[/tex]:
[tex]\[ \frac{5}{2} f(x) = \frac{5}{2} \times \frac{3}{2} \left( \frac{5}{2} \right)^{x-1} = \left( \frac{5}{2} \times \frac{3}{2} \right) \left( \frac{5}{2} \right)^{x-1} = \frac{15}{4} \left( \frac{5}{2} \right)^{x-1} \][/tex]

Simplify the right-hand side:
[tex]\[ \frac{5}{2} f(x) = \frac{3}{2} \left( \frac{5}{2} \right) \left( \frac{5}{2} \right)^{x-1} = \frac{3}{2} \left( \frac{5}{2} \right)^x \][/tex]

Since [tex]\( f(x+1) = \frac{3}{2} \left( \frac{5}{2} \right)^x \)[/tex], it is clear that:
[tex]\[ f(x+1) = \frac{5}{2} f(x) \][/tex]

Therefore, Option 1 is correct.

### Option 2: [tex]\( f(x) = \frac{5}{2} f(x+1) \)[/tex]

Let's rearrange Option 1 for Option 2:
[tex]\[ f(x+1) = \frac{5}{2} f(x) \][/tex]
To isolate [tex]\( f(x) \)[/tex], multiply both sides by [tex]\( \frac{2}{5} \)[/tex]:
[tex]\[ f(x) = \frac{2}{5} f(x+1) \][/tex]

Option 2 states [tex]\( f(x) = \frac{5}{2} f(x+1) \)[/tex], which is not consistent with the rearrangement. Thus, Option 2 is incorrect.

### Option 3: [tex]\( f(x+1) = \frac{3}{2} f(x) \)[/tex]

Calculate [tex]\( \frac{3}{2} f(x) \)[/tex]:
[tex]\[ \frac{3}{2} f(x) = \frac{3}{2} \times \frac{3}{2} \left( \frac{5}{2} \right)^{x-1} = \left( \frac{3}{2} \times \frac{3}{2} \right) \left( \frac{5}{2} \right)^{x-1} = \frac{9}{4} \left( \frac{5}{2} \right)^{x-1} \][/tex]

Since [tex]\( f(x+1) = \frac{3}{2} \left( \frac{5}{2} \right)^x \)[/tex], it is clear that:
[tex]\[ f(x+1) \neq \frac{3}{2} f(x) \][/tex]

Hence, Option 3 is incorrect.

### Option 4: [tex]\( f(x) = \frac{3}{2} f(x+1) \)[/tex]

Let's rearrange Option 1 to test Option 4:
[tex]\[ f(x+1) = \frac{5}{2} f(x) \][/tex]
To isolate [tex]\( f(x) \)[/tex], multiply both sides by [tex]\( \frac{2}{5} \)[/tex]:
[tex]\[ f(x) = \frac{2}{5} f(x+1) \][/tex]

Option 4 states [tex]\( f(x) = \frac{3}{2} f(x+1) \)[/tex], which is clearly not the same. Therefore, Option 4 is also incorrect.

Conclusively, the only correct equivalent representation is:

[tex]\[ \boxed{f(x+1) = \frac{5}{2} f(x)} \][/tex]