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\(\left(\frac{45}{7}-\frac{\frac{3}{4}x-2}{\frac{7}{20}}\right).\frac{14}{5}=10\)
\(\frac{45}{7}-\frac{\frac{3}{4}x-2}{\frac{7}{20}}=\frac{25}{7}\)
\(\frac{\frac{3}{4}x-2}{\frac{7}{20}}=\frac{20}{7}\)
\(\frac{3}{4}x-2=1\)
\(\frac{3}{4}x=3\)
\(x=4\)
Vậy x=4
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\(\frac{3}{x-5}=-\frac{4}{x+2}\)
\(\Leftrightarrow3\left(x+2\right)=-4\left(x-5\right)\)
\(\Leftrightarrow3x+6=-4x+20\)
\(\Leftrightarrow7x=14\)
\(\Leftrightarrow x=2\)
\(\frac{x}{-2}=-\frac{8}{x}\)
\(\Leftrightarrow x^2=16\)
\(\Leftrightarrow x=\pm4\)
\(-\frac{2}{x}=\frac{y}{3}\)
\(\Leftrightarrow xy=-6\)
\(\Leftrightarrow x;y\inƯ\left(-6\right)=\left\{\pm1;\pm2;\pm3;\pm6\right\}\)
Xét bảng
x | 1 | -1 | 2 | -2 | 3 | -3 | 6 | -1 |
y | -6 | 6 | -3 | 3 | -2 | 2 | -1 | 6 |
Vậy.................
\(\frac{2x-9}{240}=\frac{39}{80}\)
\(\Leftrightarrow2x-9=\frac{240.39}{80}\)
\(\Leftrightarrow2x-9=117\)
\(\Leftrightarrow2x=126\)
\(\Leftrightarrow x=63\)