To represent the total cost of the gym membership over a certain number of months, you can use the following expression:
\[ \text{Total Cost} = \text{Enrollment Fee} + (\text{Monthly Fee} \times \text{Number of Months}) \]
In this case, the enrollment fee is $1, the monthly fee is $9.99, and let \( m \) represent the number of months. Therefore, the expression can be written as:
\[ \text{Total Cost} = 1 + (9.99 \times m) \]
This expression calculates the total cost of the gym membership based on the number of months you plan to stay a member.