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\(\frac{x+10}{90}+\frac{x+20}{80}+\frac{x+30}{70}+\frac{x+40}{60}+\frac{x+50}{50}=-5\)
<=> \(\frac{x+10}{90}+1+\frac{x+20}{80}+1+\frac{x+30}{70}+1+\frac{x+40}{60}+1+\frac{x+50}{50}+1=0\)
<=> \(\frac{x+100}{90}+\frac{x+100}{80}+\frac{x+100}{70}+\frac{x+100}{60}+\frac{x+100}{50}=0\)
<=> \(\left(x+100\right)\left(\frac{1}{90}+\frac{1}{80}+\frac{1}{70}+\frac{1}{60}+\frac{1}{50}\right)=0\)
<=> x + 100 = 0
<=> x = -100
Vậy x = -100
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1.
A=\(\frac{-5x+-5y+-5z}{21}=\frac{-5\left(x+y+z\right)}{21}=\frac{-5}{21}.x+y+z\)
A= -z+z=0
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\(\frac{x+5}{95}+\frac{x+6}{94}+\frac{x+7}{93}+\frac{x+8}{92}+\frac{x+9}{91}=-5\)
\(\left(\frac{x+5}{95}+1\right)+\left(\frac{x+6}{94}+1\right)+\left(\frac{x+7}{93}+1\right)+\left(\frac{x+8}{92}+1\right)+\left(\frac{x+9}{91}+1\right)=-5+5=0\)
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a. 60%x + 0,4x + x : 3 = 2
0.6x + 0,4x + x : 3 = 2
x(0,6 + 0,4 : 3 ) = 2
\(x.\frac{1}{3}=2=>x=2:\frac{1}{3}=\frac{1}{6}\)
câu B tự làm nha .
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\(\frac{7}{2}-\left(x-\frac{7}{5}\right)=\frac{3}{5}\)
\(\frac{7}{2}-x+\frac{7}{5}=\frac{3}{5}\)
\(\frac{7}{2}-x=-\frac{4}{5}\)
\(x=\frac{43}{10}\)
Bài làm
\(\frac{7}{2}-\left(x-\frac{7}{5}\right)=\frac{3}{5}\)
\(\Rightarrow x-\frac{7}{5}=\frac{7}{2}-\frac{3}{5}\)
\(\Rightarrow x-\frac{7}{5}=\frac{35}{10}-\frac{6}{10}\)
\(\Rightarrow x-\frac{7}{5}=\frac{29}{10}\)
\(\Rightarrow x=\frac{29}{10}+\frac{7}{5}\)
\(\Rightarrow x=\frac{29}{10}+\frac{14}{10}\)
\(\Rightarrow x=\frac{43}{10}\)
Vậy \(x=\frac{43}{10}\)
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Bài làm:
Pt <=> \(\left(\frac{x-1}{2020}-1\right)+\left(\frac{x-3}{2018}-1\right)+\left(\frac{x-5}{2016}-1\right)+\left(\frac{x-7}{2014}-1\right)=4-4\)
\(\Leftrightarrow\frac{x-2021}{2020}+\frac{x-2021}{2018}+\frac{x-2021}{2016}+\frac{x-2021}{2014}=0\)
\(\Rightarrow x-2021=0\Rightarrow x=2021\)
\(\frac{5}{7}.x+x=60\)
\(< =>\frac{5x}{7}+x=60\)
\(< =>\frac{5x+7x}{7}=60\)
\(< =>7.60=12x\)
\(< =>x=35\)
\(\frac{5}{7}\cdot x+x=60\)
\(\Leftrightarrow x\cdot\left(\frac{5}{7}+1\right)=60\)
\(\Leftrightarrow x\cdot\frac{12}{7}=60\)
\(\Leftrightarrow x=35\)
Vậy x = 35