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\(\frac{2011}{2010}\times\frac{2012}{2011}\times\frac{2013}{2012}\times\frac{2014}{2013}\times\frac{1005}{1007}\)
\(=\frac{2014}{2010}\times\frac{1005}{1007}\)
\(=\frac{2\times1007\times1005}{2\times1005\times1007}\)
\(=1\)
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1 1/9 x 1 1/10 x 1 1/11 x ... x 1 1/2011
=10/9 x 11/10 x 12/11 x ... x 2012/2011
khử
còn 2012/9
=\(\frac{10}{9}\)x\(\frac{11}{10}\)x\(\frac{12}{11}\)x.........x\(\frac{2012}{2011}\)
=\(\frac{2012}{9}\)
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(x + 1) + (2.x + 2) + (3.x + 3) + ... + (100.x + 100) = 45450
(x + 2.x + 3.x + ... + 100.x) + (1 + 2 + 3 + ... + 100) = 45450
x.(1 + 2 + 3 + ... + 100) + (1 + 2 + 3 + ... + 100) = 45450
(1 + 2 + 3 + ... + 100).(x + 1) = 45450
(1 + 100).100:2.(x + 1) = 45450
101.50.(x + 1) = 45450
5050.(x + 1) = 45450
x + 1 = 45450 : 5050
x + 1 = 9
x = 9 - 1
x = 8
Vậy x = 8
Ủng hộ mk nha ☆_☆^_-
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2(x-1)=6(10-x)
<=>2x-2=60-6x
<=>2x+6x=60+2
<=>8x=62
<=>x=62:8
<=>x=7,75
=> 2x - 2 = 60 - 6x
=> 2x + 6x = 2 + 60
=> 8x = 62
=> x = 7,75
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\(\dfrac{1}{1\cdot2}+\dfrac{1}{2\cdot3}+\dfrac{1}{3\cdot4}+.......+\dfrac{1}{x\cdot\left(x+1\right)}=\dfrac{122}{123}\)
\(\Leftrightarrow1-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+......+\dfrac{1}{x}-\dfrac{1}{x+1}=\dfrac{122}{123}\)
\(\Leftrightarrow1-\dfrac{1}{x+1}=\dfrac{122}{123}\)
\(\Leftrightarrow\dfrac{1}{x+1}=\dfrac{1}{123}\)
\(\Leftrightarrow x=122\)
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