The range of a function is the set of possible values that can be obtained from the dependent variable. The range of the function is:
Given that:
Let the number of months be t. So, the function C(t) is calculated as follows:
The range is calculated as follows:
The smallest possible value of t is 0 i.e. when no monthly subscription is done.
So, we have:
And the highest is i.e. for a large value of t
So, we have:
Hence, the range of the function is:
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