D=1/6+1/15+1/35+1/51x53
ND
Những câu hỏi liên quan
a=1/1x2 + 1/2x3+ 1/3x4 +...1/99x100
b=4/1x3+4/3x5+4/5x7 +...+4/51x53
a=1/1x2+1/2x3+....+1/99x100
a=1-1/2+1/2-1/3+....+1/99-1/100
a=1-1/100
a=99/100
b=4/1x3+4/3x5+.....+4/51x53
b=2x(2/1x3+2/3x5+....+2/51x53)
b=2x(1-1/3+1/3-1/5+...+1/51-1/53)
b=2x(1-1/53)
b=2x52/53
b=104/53
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a/ 1/2 + 5/6 + 11/12 + 19/20
b/ 1/2 + 5/6 + 11/12 + 19/20 + 29/30 + 41/42
c/ (1-1/3) + (1-1/15) + (1-1/35) + (1-1/63)
d/ 1/2 + 5/6 + 11/12 + ... + 9899/9900
e/ 2/3 + 14/15 + 34/35 +62/63
f/ 2/3 + 14/15 + 34/35 + ... + 9998/9999
cái này tính cái gì thế
ko hiểu
tinh :
a. A=1/1 x2 cong 1/2x3 + 1/3x4 + ... + 1/99x100
b. B=4/1x3+4/3x5 +4/5+7 +... +4/51x53
a)(5+1/5-2/9)-(2-1/23-3/35+5/6)-(8+2/7-1/18)
b) 1/3-3/4(-3/5+1/64- -2/9-1/36+1/15
c) -5/7-(-5/67)+13/10+1/2+(-1/6)+1 3/14-(-2/5)
d)3/5:(-1/15-1/6)+3/5:(-1/3-1 1/15)
NB
6 tháng 3 2023 lúc 18:58
2. Tính: A) 1/3 + 1/5 - 1/4. B) 7/8 - ( 1/4 + 2/5 ). C) 5/11 - ( 3/5 - 6/11 ). D) 5/7 - ( 19/35 - 6/15 ).
`A) 1/3 + 1/5 - 1/4 = 20/60 + 12/60 - 15/60 = 17/60`
` B) 7/8 - ( 1/4 + 2/5 ) = 7/8 - 2/4 -2/5 = 5/8-2/8 = 9/40`
` C) 5/11 - ( 3/5 - 6/11 ) = 5/11 - 3/55 = 25/55 - 3/55 = 22/55=2/5 `
` D) 5/7 - ( 19/35 - 6/15 ) = 5/7 - 1/7 = 4/7 `
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NB
6 tháng 3 2023 lúc 19:11
2. Tính: A) 1/3 + 1/5 - 1/4. B) 7/8 - ( 1/4 + 2/5 ). C) 5/11 - ( 3/5 - 6/11 ). D) 5/7 - ( 19/35 - 6/15 ).
`1/3 + 1/5 -1/4`
`= 5/15 + 3/15 -1/4`
`= 8/15 -1/4`
`= 17/60`
__
`7/8 -(1/4 + 2/5)`
`= 7/8-1/4 - 2/5`
`= 7/8 - 2/8 -2/5`
`= 5/8 -2/5`
`= 9/40`
__
`5/11-(3/5 -6/11)`
`= 5/11 -3/5 +6/11`
`= (5/11 + 6/11)-3/5`
`= 1 -3/5`
`= 5/5-3/5`
`=2/5`
__
`5/7 - ( 19/35 - 6/15)`
`= 5/7 - 19/35 + 6/15`
`= 25/35 -19/35 + 6/15`
`=6/35 +6/15`
`=4/7`
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Câu 2. phân số bằng \(\dfrac{2}{7}\) là:
A. \(\dfrac{1}{2}\) B.\(\dfrac{12}{35}\) C.\(\dfrac{6}{21}\) D.\(\dfrac{15}{35}\)
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1. Tính tổng
a, A=1/2.3 + 1/3.4 + ... + 1/99.100
b, B= 5/1.4 + 5/4.7 + ... + 5/100.103
c, C= 1/15 +1/35 + ... + 1/2499
d, D=1/1.6 + 1/6.11 + 1/11.16 + ... +1/(5n+1).(5n+6)
mn ơi mình đang cần gấp
a: =1/2-1/3+1/3-1/4+...+1/99-1/100
=1/2-1/100=49/100
b; =5/3(1-1/4+1/4-1/7+...+1/100-1/103)
=5/3*102/103
=510/309=170/103
c: =1/2(1/3-1/5+1/5-1/7+...+1/49-1/51)
=1/2*16/51=8/51
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Tính nhanh:
a)1/3+1/15+1/35+...1/195
b)6/8+6/56+6/140+...6/416
c)1/10+1/15+1/21+...1/66
a)\(\frac{1}{3}+\frac{1}{15}+\frac{1}{35}+...+\frac{1}{195}\)
Đặt \(C=\frac{1}{10}+\frac{1}{15}+\frac{1}{21}+...+\frac{1}{66}\)
\(\Rightarrow\frac{1}{2}C=\frac{1}{20}+\frac{1}{30}+\frac{1}{42}+...+\frac{1}{132}\)
\(\Rightarrow\frac{1}{2}C=\frac{1}{4.5}+\frac{1}{5.6}+\frac{1}{6.7}+...+\frac{1}{11.12}\)
\(\Rightarrow\frac{1}{2}C=\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}+\frac{1}{6}-\frac{1}{7}+...+\frac{1}{11}-\frac{1}{12}\)
\(\Rightarrow\frac{1}{2}C=\frac{1}{4}+\left(-\frac{1}{5}+\frac{1}{5}\right)+\left(-\frac{1}{6}+\frac{1}{6}\right)+...+\left(-\frac{1}{11}+\frac{1}{11}\right)-\frac{1}{12}\)\(\Rightarrow\frac{1}{2}C=\frac{1}{4}+0+0+...+0-\frac{1}{12}\)
\(\Rightarrow\frac{1}{2}C=\frac{1}{4}-\frac{1}{12}\)
\(\Rightarrow\frac{1}{2}C=\frac{3}{12}-\frac{1}{12}\)
\(\Rightarrow\frac{1}{2}C=\frac{2}{12}\)
\(\Rightarrow\frac{1}{2}C=\frac{1}{6}\)
\(\Rightarrow C=\frac{1}{6}:\frac{1}{2}\)
\(\Rightarrow C=\frac{1}{6}\cdot2\)
\(\Rightarrow C=\frac{2}{6}=\frac{1}{3}\)
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