To find [tex]\( f(5) \)[/tex] for the function [tex]\( f(r) = 3.14 \times r^2 \)[/tex], we need to substitute [tex]\( r \)[/tex] with 5 and then evaluate the expression. Let's go through this step by step:
1. Start with the function: [tex]\( f(r) = 3.14 \times r^2 \)[/tex].
2. Substitute [tex]\( r = 5 \)[/tex] into the function: [tex]\( f(5) = 3.14 \times 5^2 \)[/tex].
3. Calculate the square of 5: [tex]\( 5^2 = 25 \)[/tex].
4. Multiply this result by 3.14: [tex]\( 3.14 \times 25 \)[/tex].
So, we have:
[tex]\[ f(5) = 3.14 \times 25 = 78.50 \][/tex]
Therefore, [tex]\( f(5) \)[/tex] is [tex]\( 78.50 \)[/tex].
The correct answer is:
D. 78.50
