1/2+1/4+1/8+……+1/256
=(1-1/2)+(1/2-1/4)+(1/4-1/8)+......+(1/128-1/256)
=1-1/2+1/2-1/4+1/4-1/8+......+1/128-1/256
=1-1/256
=255/256
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Các câu hỏi tương tự
(1/2+1/4+1/8.....+1/256+1/512)*2=511/256
tính nhanh ;
a) (1-1/2)x(1-1/3)x(1-1/4)x....x(1-1/2014)x(1-1/2015)
b) 1/2+1/4+1/8+....+1/256
c) 5/2+5/4+5/8+....+5/256
Tính:1/2+1/4+1/8+...+1/256=A/256
A bằng :
tính nhanh
a) (1-1/2)x(1-1/3)x(1-1/4)x...x(1-1/2014)x(1-1/2015).
b) 1/2 +1/4+1/8+...+1/256.
c)5/2+5/4+5/8+...+5/256
d)14,35+(13,7-13,6)x1
A= 1/2 + 1/4 + 1/8 +...+1/256 +1/512
1/2+1/4+1/8+1/16+...+1/256+1/512
1/2 + 1/4 + 1/8 + 1/16 +...+ 1/256 + 1/512
1/2+1/4+1/8+1/16...+1/128+1/256=
1/2+1/4+1/8+1/16+........+1/256+1/512