To represent the information that \( y \) is a function of \( x \) and that \( y = 5 \) when \( x = 3 \) using function notation, we write:
- \( f(3) = 5 \)
This indicates that when the input to the function \( f \) is 3, the output is 5.
Among the options provided, the correct representation is:
E. f(3) = 5