a)1/2+1/6+1/12+........+1/9900+1/10100
b)1/2+1/4+1/8+....+1/256+1/512
Những câu hỏi liên quan
a)1/2+1/6+1/12+.........+1/9900+1/10100 = ?
b)1/2+1/4+1/8+...........+1/256+1/512 = ?
a) trieu dang làm rồi
b) A= 1/2 + 1/4+ 1/8+ 1/16 + 1/32 + 1/64 + 1/128 + 1/256 + 1/512
A = 1 - 1/2 + 1/2- 1/4 + 1/4 - 1/8 + 1/8 - 1/16 + 1/16 - 1/32 + 1/32 - 1/64 + 1/64 - 1/128 + 1/128 - 1/256 - 1/256 - 1/512
A = 1 - 1/512
A = 511/512
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tinh bang cach thuan tien nhat
1/2+1/6+1/12+1/20
1/2+1/6+1/12+1/20+..........+1/9900
1/2+1/3+1/4+1/8+1/16
1/2+1/3+1/4+1/8+1/16+........+1/512
\(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}\)
\(=\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}\)
\(=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+\frac{1}{5}\)
\(=1-\frac{1}{5}\)
\(=\frac{4}{5}\)
\(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+...+\frac{1}{9900}\)
\(=\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+...+\frac{1}{98.99}+\frac{1}{99.100}\)
\(=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+....+\frac{1}{98}-\frac{1}{99}+\frac{1}{99}-\frac{1}{100}+\frac{1}{100}\)
\(=1-\frac{1}{100}\)
\(=\frac{99}{100}\)
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Tính nhanh:
a)1/2+1/6+1/12+...........+1/1990+1/10100
b)1/2+1/4+1/8+.............+1/256+1/512
Tinh :
1+2+2^2+2^3+...+2^100
Tim x
X : 2 +x:6 +x:12+...+x:9900 = 99
x :(1/2)+x:(1/4)+x:(1/8) +...+ x:(1/512)=511
Đặt A=1+2+22+23+...+2100
suy ra 2A=2+22+23+...+2100
suy ra 2A-A=(2+22+23+...+2101)-(1+2+22+23+...+2100)
=2101-1
Vậy 1+2+22+23+...+2100=2101-1
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A=1+2+2^2+2^3+...+2^100
2A=2+22+23+24+...+2101
2A-A=2101-1
Vậy A= 2101-1
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Xem thêm câu trả lời
1/2+1/4+1/6+1/8+1/16+...+1/256+1/512 = ?
Đặt A=1/2+1/4+1/6+1/8+1/16+...+1/256+1/512
=(1/2+1/4+1/8+1/16+...+1/256+1/256-1/512)+1/6
=(1-1/2+1/2-1/4+1/4-1/8+1/8-1/16+...+1/128-1/256+1/256-1/512)+1/6
=1-1/512+1/6
=1789/1536
Vậy A=1789/1536
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A= 1/2 + 1/4 + 1/8 +...+1/256 +1/512
\(A=\dfrac{1}{2}+\dfrac{1}{2^2}+\dfrac{1}{2^3}+...+\dfrac{1}{2^9}\\ 2A=1+\dfrac{1}{2}+\dfrac{1}{2^2}+...+\dfrac{1}{2^8}\\ 2A-A=\left(1+\dfrac{1}{2}+...+\dfrac{1}{2^8}\right)-\left(\dfrac{1}{2}+\dfrac{1}{2^2}+...+\dfrac{1}{2^9}\right)\\ A=1-\dfrac{1}{2^9}=\dfrac{511}{512}\)
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(1/2+1/4+1/8.....+1/256+1/512)*2=511/256
A=1/2+1/4+1/8.....+1/256+1/512
2A=1+1/2+1/4+1/8...1/256
A=(1+1/2+1/4+1/8...1/256)-(1/2+1/4+1/8.....+1/256+1/512)
A=1-1/512
A=511/512
511/512
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Tính nhanh tổng A biết :A =1/2+1/4+1/8+1/16+....+1/256+1/512
Ta có: A =1/2+1/4+1/8+1/16+....+1/256+1/512
=> 2A = 1 + 1/2 + 1/4 + 1/8 + ...+ 1/128 + 1/256
=> 2A - A = (1 + 1/2 + 1/4 + 1/8 + ...+ 1/128 + 1/256 -(1/2+1/4+1/8+1/16+....+1/256+1/512 )
A = 1 - 1/512 = 511/512
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Tính nhanh:
1/2+1/4+1/8+1/16+1/32+1/64+1/12+1/256+1/512.
nhanh lên mình đang vội
1/2 + 1/4+ 1/8+ 1/16 + 1/32 + 1/64 + 1/128 + 1/256 + 1/512
= 1 – 1/2 + 1/2- 1/4 + 1/4 – 1/8 + 1/8 – 1/16 + 1/16 – 1/32 + 1/32 – 1/64 + 1/64 – 1/128 + 1/128 – 1/256 – 1/256 – 1/512
= 1 – 1/512
= 511/512
hok tot
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