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\(\Leftrightarrow\left(x-3\right)\left(\dfrac{1}{13}+\dfrac{1}{14}-\dfrac{1}{15}-\dfrac{1}{16}\right)=0\)
=>x-3=0
hay x=3
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a: \(\Leftrightarrow\left(x-\dfrac{2}{3}\right)\cdot\dfrac{5}{6}=\dfrac{-4}{15}+\dfrac{2}{5}=\dfrac{-4+6}{15}=\dfrac{2}{15}\)
=>x-2/3=4/25
hay x=62/75
b: \(\Leftrightarrow x+\dfrac{1}{9}=\dfrac{2}{45}\)
=>x=2/45-1/9=2/45-5/45=-3/45=-1/15
c: \(\dfrac{17}{18}-\left(x+\dfrac{7}{12}\right)=\dfrac{1}{9}\)
=>x+7/12=17/18-1/9=17/18-2/18=15/18=5/6
=>x=5/6-7/12=10/12-7/12=1/4
d: \(\Leftrightarrow\left(x+\dfrac{13}{21}\right)\cdot\dfrac{7}{12}=\dfrac{13}{15}-\dfrac{7}{10}=\dfrac{26-21}{30}=\dfrac{1}{6}\)
=>x+13/21=1/6:7/12=1/6x12/7=12/42=2/7
=>x=2/7-13/21=-1/21
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Ta có: \(2x^3-1=15\Leftrightarrow x^3=8\Rightarrow x=2\)
\(\Rightarrow\dfrac{18}{9}=\dfrac{y-25}{16}=\dfrac{z+9}{25}\Rightarrow\left\{{}\begin{matrix}\dfrac{y-25}{16}=2\Rightarrow y=57\\\dfrac{z+9}{25}=2\Rightarrow z=41\end{matrix}\right.\)
Vậy \(B=x+y+z=2+57+41=100\)
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`2x^3-1=15=>2x^3=16=>x^3=8=>x=2`
Có:`[x+16]/9=[y-25]/16`
`=>[2+16]/9=[y-25]/16=>y=57`
Có:`[x+16]/9=[z+9]/25`
`=>[2+16]/9=[z+9]/25=>z=41`
Ta có:`B=x+y+z=2+57+41=100`
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`a)-2/5+5/6(x-2/3)=-4/15`
`5/6(x-2/3)=-4/15+2/5=2/15`
`x-2/3=2/15:5/6=4/25`
`x=4/25+2/3=62/75`
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`b)-x-1/9=-2/45`
`-x=-2/45+1/9`
`-x=1/15`
`x=-1/15`
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`c)17/18-(x+7/12)=1/9`
`x+7/12=17/18-1/9=5/6`
`x=5/6-7/12=1/4`
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`d)13/15-(13/21+x)xx7/12=7/10`
`(13/21+x)xx7/12=13/15-7/10=1/6`
`13/21+x=1/6:7/12=2/7`
`x=2/7-13/21=-1/3`
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a: \(\Leftrightarrow\left(x-\dfrac{2}{3}\right)\cdot\dfrac{5}{6}=\dfrac{-4}{15}+\dfrac{2}{5}=\dfrac{-4+6}{15}=\dfrac{2}{15}\)
=>x-2/3=4/25
hay x=62/75
b: \(\Leftrightarrow x+\dfrac{1}{9}=\dfrac{2}{45}\)
=>x=2/45-1/9=2/45-5/45=-3/45=-1/15
c: \(\dfrac{17}{18}-\left(x+\dfrac{7}{12}\right)=\dfrac{1}{9}\)
=>x+7/12=17/18-1/9=17/18-2/18=15/18=5/6
=>x=5/6-7/12=10/12-7/12=1/4
d: \(\Leftrightarrow\left(x+\dfrac{13}{21}\right)\cdot\dfrac{7}{12}=\dfrac{13}{15}-\dfrac{7}{10}=\dfrac{26-21}{30}=\dfrac{1}{6}\)
=>x+13/21=1/6:7/12=1/6x12/7=12/42=2/7
=>x=2/7-13/21=-1/21
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`#ava`
Bài `4` : Tìm `x:`
`a)-2/5+5/6(x-2/3)=-4/15`
`5/6(x−2/3)=−4/15+2/5`
`5/6(x−2/3)=−4/15+6/15`
`5/6(x−2/3)=2/15`
`x−2/3=2/15:5/6`
`x−2/3=12/75`
`x=12/75+2/3`
`x=62/75`
`b)−x−1/9=−2/45`
`−x=−2/45+1/9`
`−x=1/15`
`->x=−1/15`
`c)17/18−(x+7/12)=1/9`
`x+7/12=17/18−1/9`
`x+7/12=5/6`
`x=5/6−7/12`
`x=1/4`
`d)13/15-(13/21+x).7/2=7/10`
`(13/21+x).7/12=1/6`
`13/21+x=2/7`
`x=-1/3`
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`#ava`
Pháp: \(1294246 : 59 , 2 ≈ 21862 ( U S D /\)người\()\)
Đức : \(1872992 : 82 , 2 ≈ 22786 ( U S D /\)người\()\)
Ba Lan:\(157585 : 38 , 6 ≈ 4083 ( U S D /\)người\()\)
CH Séc:\(50777 : 10 , 3 ≈ 4930 ( U S D /\)người\()\)
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