- Simplify the following products.
(1-r)(1+r) =

(1-r)(1+r+r^2) =

(1-r)(1+r+r^2+r^3) =

(1-r)(1+r+r^2+r^3+ \cdots + r^n) = - Assume
r\neq 1 . Using what you calculated above, find a closed-form expression for the following finite sum.1+r+r^2+r^3+ \cdots + r^n =

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