In this problem
we have an exponential growth function of the form
where
a is the initial value -----> a=1 (one member)
b is the base of the exponential function
substitute the value of a
Find out the value of b
we know that
The membership of an online club is tripling every day
that means
For x=1
the value of y=3
substitute
therefore
The exponential equation
Find out the rate
b=1+r
3=1+r
r=2
r=200%
therefore
The function that models the situation is
where
x is the number of days
y is the number of membership