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\(\frac{x}{6}+\frac{x}{10}+\frac{x}{15}+\frac{x}{21}+\frac{x}{28}+\frac{x}{39}=\frac{8}{9}.\)

\(\Rightarrow x.\left(\frac{1}{6}+\frac{1}{10}+\frac{1}{15}+\frac{1}{21}+\frac{1}{28}+\frac{1}{39}\right)=\frac{8}{9}\)

\(\Rightarrow x.\frac{23}{52}=\frac{8}{9}\)

\(\Rightarrow x=\frac{426}{207}\)

Study well 

21 tháng 8 2019

\(\frac{x}{6}+\frac{x}{10}+\frac{x}{15}+\frac{x}{21}+\frac{x}{28}+\frac{x}{39}=\frac{8}{9}\)

<=> x\(\left(\frac{1}{6}+\frac{1}{10}+\frac{1}{15}+\frac{1}{21}+\frac{1}{28}+\frac{x}{39}\right)=\frac{8}{9}\)

<=> x = \(\frac{8}{9}:\frac{23}{52}\)

<=> x = \(\frac{416}{207}\)

3 tháng 3 2018

\(\frac{x}{6}+\frac{x}{10}+\frac{x}{15}+\frac{x}{21}+\frac{x}{28}+\frac{x}{36}+\frac{x}{45}+\frac{x}{55}+\frac{x}{66}+\frac{x}{78}+\frac{x}{78}=\frac{220}{39}\)

\(\Leftrightarrow x\left(\frac{1}{6}+\frac{1}{10}+\frac{1}{15}+\frac{1}{21}+\frac{1}{28}+\frac{1}{36}+\frac{1}{45}+\frac{1}{55}+\frac{1}{66}+\frac{1}{78}+\frac{1}{78}\right)=\frac{220}{39}\)

\(\Leftrightarrow x\cdot\frac{20}{39}=\frac{220}{39}\Rightarrow x=11\)

3 tháng 3 2018

\(\frac{x}{6}+\frac{x}{10}+\frac{x}{15}+\frac{x}{21}+\frac{x}{28}+\frac{x}{36}+\frac{x}{45}+\frac{x}{55}+\frac{x}{66}+\frac{x}{78}+\frac{x}{78}=\frac{220}{39}\)

\(=>x=\frac{1}{6}+\frac{1}{10}+\frac{1}{15}+\frac{1}{21}+\frac{1}{28}+\frac{1}{36}+\frac{1}{45}+\frac{1}{55}+\frac{1}{66}+\frac{1}{78}+\frac{1}{78}=\frac{220}{39}\)

\(x\cdot\frac{20}{39}=\frac{220}{39}\)

\(x=\frac{220}{39}:\frac{20}{39}=11\)

28 tháng 2 2018

bằng 2

29 tháng 3 2019

đáp án đúng = 2

29 tháng 1 2019

\(\frac{3}{x-5}=-\frac{4}{x+2}\)

\(\Leftrightarrow3\left(x+2\right)=-4\left(x-5\right)\)

\(\Leftrightarrow3x+6=-4x+20\)

\(\Leftrightarrow7x=14\)

\(\Leftrightarrow x=2\)

\(\frac{x}{-2}=-\frac{8}{x}\)

\(\Leftrightarrow x^2=16\)

\(\Leftrightarrow x=\pm4\)

\(-\frac{2}{x}=\frac{y}{3}\)

\(\Leftrightarrow xy=-6\)

\(\Leftrightarrow x;y\inƯ\left(-6\right)=\left\{\pm1;\pm2;\pm3;\pm6\right\}\)

Xét bảng

x1-12-23-36-1
y-66-33-22-16

Vậy.................

\(\frac{2x-9}{240}=\frac{39}{80}\)

\(\Leftrightarrow2x-9=\frac{240.39}{80}\)

\(\Leftrightarrow2x-9=117\)

\(\Leftrightarrow2x=126\)

\(\Leftrightarrow x=63\)

15 tháng 2 2019

\(\text{3 Giải}\)

\(\frac{x+1}{6}=\frac{8}{3}=\frac{16}{6}\Rightarrow x+1=16\Rightarrow x=15.\text{Vậy: x=15}\)