Tính tổng:1 + 1/2 + 1/4 + 1/8 + 1/16 + ...+ 1/512 + 1/1024
Tính nhanh tổng sau:
1/2 + 1/4 + 1/8 + 1/16 + 1/32 + 1/64 + 1/128 + 1/256 + 1/512 + 1/1024
bằng 0,9990234375
tính nhanh tổng sau:
1/2+1/4+1/8+1/16+1/64+1/128+1/256+1/512+1/1024
các bạn giả gips mik với nha!
tính nhanh \(\dfrac{1}{2}\) +\(\dfrac{1}{4}\) +\(\dfrac{1}{8}\)+\(\dfrac{1}{16}\) +.....+\(\dfrac{1}{512}\) +\(\dfrac{1}{1024}\)
Đặt A=1/2+1/4+1/8+..+1/1024
Ax2=1+1/2+1/4+1/8+..+1/512( Nhân cả 2 vế với 2)
Ax2-A=(1+1/2+1/4+1/8+..+1/512)-(1/2+1/4+1/8+..+1/1024)
<=>A=1-1/1024
<=>A=1023/1024
Vậy biểu thức đã cho = 1023/1024
Tính tổng:
A=(1-1/2)+(1-1/4)+(1-1/8)+...+(1-1/512)+(1+1/1024)
1/2+=1/4+1/8+1/16+...+1/512+1/1024
A=\(\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+...+\frac{1}{1024}\)
=\(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{4}+\frac{1}{4}-\frac{1}{8}+...+\frac{1}{512}-\frac{1}{1024}\)
=1-1/1024
=1023/1024
tính nhanh ;
1234.5678.(630 -315) :1996
319.45+ 55.319 /1995.1996 -1991.1995
1988.1996+1997.11+1985 /1997.1996-1995.1996
(1+2+4+8+.....+512) .(101.102-101.101-50-51) /2+4+6+8+16+....+1024+2048
(1+2+4+8+....+512).(135135.246-246246.135)/2+4+8+16+....+1024+2048
A=1/2+1/4+1/8+1/16+.........+1/512+1/1024 = ?
Đặt S = 1/2 + 1/4 + 1/8 + 1/16 + ...
==> 2S = 1 + 1/2 + 1/4 + 1/8 + 1/16 + ...
2S = 1 + S
==> S = 1
Ta có 2xA=1+1/2+...+1/512
Do đó: A=2xA-A=1-1/1024=1023/1024.
Tính nhanh:
1/2+1/4+1/8+1/16+...+1/512+1/1024
Ai nhanh mình tích 3 cái
1/2=1/1-1/2
1/4=1/2-1/4
1/8=1/4-1/8
...................
1/1024=1/512-1/1024
Đặt biểu thức=A
A=1/1-1/2+1/2-1/4+1/4-1/8+........+1/512-1/1024
A=1/1-1/1024
A=1023/1024
bạn thấy cách của mik có dễ hiểu ko,nếu dễ hiểu thì k nha
có cách khác : 1/2+ 1/4= 3/4
1/2+ 1/4 +1/8 = 7/8
vậy :1/2+ 1/4 +1/8 + ....+ 1/1024 =1023/1024
Gọi A = 1/2 + 1/4 + 1/8 + 1/1024
2 x A = 1 + 1/2 + 1/4 +... +1/512
2 x A - A = ( 1 + 1/2 + 1/4 +... +1 /512 ) - ( 1/2 + 1/4 + 1/8 +... + 1/ 1024 )
A = 1 - 1/1024
A = 1023/1024
Vậy A = 1023/1024
A= 1/2 + 1/4 + 1/8 +1/16 +1/32 + 1/64 +1/128 + 1/256 + 1/512 + 1/1024
tìm A/tính nhanh
A = 1/2 + 1/4 + 1/8 + ... + 1/1024
2A = 1 + 1/2 + 1/4 + ... + 1/512
2A - A = (1 + 1/2 + 1/4 + ... + 1/512) - (1/2 + 1/4 + 1/8 + ... + 1/1024)
A = 1 - 1/1024
A = 1023/1024
\(A=\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+....+\frac{1}{1024}\)
\(\Rightarrow2A=1+\frac{1}{2}+\frac{1}{4}+......+\frac{1}{512}\)
\(\Rightarrow A=2A-A=1-\frac{1}{1024}\)
\(A=\frac{1023}{1024}\)
A=\(\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+...+\frac{1}{512}+\frac{1}{1024}\)
2 x A=\(1+\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+...+\frac{1}{512}\)
2 x A - A = \(\left(1+\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+...+\frac{1}{512}\right)-\left(\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+...+\frac{1}{512}+\frac{1}{1024}\right)\)
A=\(1-\frac{1}{1024}\)
A=\(\frac{1023}{1024}\)