How does [tex]f(x) = 1.5^x[/tex] change over the interval from [tex]x = 2[/tex] to [tex]x = 3[/tex]?

A. [tex]f(x)[/tex] decreases by 1.5
B. [tex]f(x)[/tex] increases by [tex]50\%[/tex]
C. [tex]f(x)[/tex] decreases by a factor of 1.5
D. [tex]f(x)[/tex] increases by [tex]150\%[/tex]



Answer :

Let's explore how the function [tex]\( f(x) = 1.5^x \)[/tex] changes from [tex]\( x = 2 \)[/tex] to [tex]\( x = 3 \)[/tex].

1. Evaluate the function at [tex]\( x = 2 \)[/tex]:
[tex]\[ f(2) = 1.5^2 = (1.5 \times 1.5) = 2.25 \][/tex]

2. Evaluate the function at [tex]\( x = 3 \)[/tex]:
[tex]\[ f(3) = 1.5^3 = (1.5 \times 1.5 \times 1.5) = 3.375 \][/tex]

3. Calculate the absolute change from [tex]\( x = 2 \)[/tex] to [tex]\( x = 3 \)[/tex]:
[tex]\[ \Delta f = f(3) - f(2) = 3.375 - 2.25 = 1.125 \][/tex]

4. Calculate the percentage change:
[tex]\[ \text{Percentage change} = \left( \frac{\Delta f}{f(2)} \right) \times 100 = \left( \frac{1.125}{2.25} \right) \times 100 \][/tex]

5. Simplify the fraction:
[tex]\[ \frac{1.125}{2.25} = \frac{1}{2} = 0.5 \][/tex]

6. Convert this ratio into a percentage:
[tex]\[ 0.5 \times 100 = 50\% \][/tex]

Therefore, [tex]\( f(x) \)[/tex] increases by [tex]\( 50\% \)[/tex] from [tex]\( x = 2 \)[/tex] to [tex]\( x = 3 \)[/tex]. Hence, the correct answer is:

[tex]\( f(x) \)[/tex] increases by [tex]\( 50\% \)[/tex] (choice b).