Question

Rút gọn: A =  1/2+1/2²+1/2³+....+1/2¹⁰⁰

Answer 1

1/2.A=1/2²+1/2³+...+1/2¹⁰¹

=>1/2A-A=1/2¹⁰¹-1/2

=>-1/2A=1/2¹⁰¹-1/2

A=(1/2¹⁰¹-1/2):(-1/2)=(1/2¹⁰¹-1/2).(-2)

=1-1/2¹⁰⁰