Determine if the function \( f(x) = 3x + 5 \) is linear.

Step 1 ：A function is linear if it can be written in the form \( f(x) = mx + b \), where \( m \) and \( b \) are constants.

Step 2 ：The given function is \( f(x) = 3x + 5 \), which is in the form \( f(x) = mx + b \), with \( m = 3 \) and \( b = 5 \).