High School

If [tex]f(x)=\left(\frac{1}{9}\right)\left(9^x\right)[/tex], what is [tex]f(3)[/tex]?

A. [tex]\frac{1}{729}[/tex]
B. 81
C. [tex]\frac{1}{81}[/tex]
D. 729

Answer :

To find [tex]\( f(3) \)[/tex] for the function [tex]\( f(x) = \left(\frac{1}{9}\right)\left(9^x\right) \)[/tex], let's follow these steps:

1. Identify the function:
We have [tex]\( f(x) = \left(\frac{1}{9}\right) \times 9^x \)[/tex].

2. Substitute [tex]\( x = 3 \)[/tex] into the function:
Replace [tex]\( x \)[/tex] in the function with 3:
[tex]\[
f(3) = \left(\frac{1}{9}\right) \times 9^3
\][/tex]

3. Calculate [tex]\( 9^3 \)[/tex]:
[tex]\( 9^3 \)[/tex] means multiplying 9 by itself three times:
[tex]\[
9 \times 9 \times 9 = 81 \times 9 = 729
\][/tex]

4. Multiply by [tex]\(\frac{1}{9}\)[/tex]:
Now, multiply the result of [tex]\( 9^3 \)[/tex] by [tex]\(\frac{1}{9}\)[/tex]:
[tex]\[
f(3) = \left(\frac{1}{9}\right) \times 729 = \frac{729}{9}
\][/tex]

5. Simplify the fraction:
Divide 729 by 9:
[tex]\[
\frac{729}{9} = 81
\][/tex]

Thus, the value of [tex]\( f(3) \)[/tex] is 81. Therefore, the correct answer is:

B. 81