Đặt A = 1/2 + 1/4 + 1/8 + .........+ 1/256 + 1/512
A x 2 = ( 1/2 + 1/4 + 1/8 +.........+ 1/256 + 1/512 ) x 2
A x 2 = 1 + 1/2 + 1/4 + ..........+ 1/128 + 1/256
A x 2 - A = 1 + 1/2 + 1/4 + ..........+ 1/128 + 1/256
- 1/2 - 1/4 - 1/8 -...........- 1/256 - 1/512
A = 1 - 1/512
A = 511/512
Vậy giá trị biểu thức là 511/512
\(\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+...+\frac{1}{256}+\frac{1}{512}\)
\(A=\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}+\frac{1}{32}+\frac{1}{64}+\frac{1}{128}+\frac{1}{256}+\frac{1}{512}\)
A = \(\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}+\frac{1}{32}+\frac{1}{64}+\frac{1}{128}+\frac{1}{256}+\frac{1}{512}\)
TÍNH TỔNG DÃY SAU:
\(\frac{1}{4}+\frac{1}{16}+\frac{1}{64}+\frac{1}{128}+\frac{1}{256}+\frac{1}{512}\)
\(A=\frac{1}{4}+\frac{1}{8}+\frac{1}{16}+\frac{1}{32}+\frac{1}{64}+\frac{1}{128}+\frac{1}{256}+\frac{1}{512}\)
Trình bày rõ ràng giúp ạ..!!! :))))))))))
Bài 1 : Tính nhanh :
\(1\frac{1}{2}+2\frac{1}{4}+3\frac{1}{8}+4\frac{1}{16}+.....+8\frac{1}{250}+9\frac{1}{512}\)
Tính : \(\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}+\frac{1}{32}+\frac{1}{64}+\frac{1}{128}+\frac{1}{256}\)
tính biểu thức sau
\(a=\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+..........+\frac{1}{512}+\frac{1}{1024}\)
tính nhanh:
\(A=1+\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}+...+\frac{1}{512}+\frac{1}{1024}\)