Determine whether the function \( f(x) = 3x + 7 \) is linear.

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

Step 2 ：In the given function \( f(x) = 3x + 7 \), we can see that it is in the form of a linear function with \( m = 3 \) and \( b = 7 \).