Final answer:
To express 1/(1-y) using the geometric series formula, substitute a = 1 and r = y into the formula.
Step-by-step explanation:
The geometric series formula is given by:
S = a / (1 - r)
In this formula, a represents the first term of the series, and r represents the common ratio between the terms.
By substituting a = 1 and r = y into the formula, we can express 1 / (1 - y) using the geometric series formula. The equation becomes:
1 / (1 - y) = 1 / (1 - y)