\(1,\frac{-x}{15}=\frac{10}{25}\)
\(\Leftrightarrow\frac{-x}{15}=\frac{2}{5}\Leftrightarrow\left(-x\right).5=2.15\)
\(\Leftrightarrow\left(-x\right).5=30\)
\(\Leftrightarrow-x=6\Rightarrow x=-6\)
\(2,\frac{x+1}{14}=\frac{10}{35}\)
\(\Leftrightarrow\frac{x+1}{14}=\frac{2}{7}\)
\(\Leftrightarrow\left(x+1\right).7=2.14\)
\(\Leftrightarrow7x+7=28\)
\(\Leftrightarrow7x=21\)
\(\Rightarrow x=3\)
\(3,\frac{\left|x+2\right|}{26}=\frac{12}{39}\)
\(\Leftrightarrow\frac{\left|x+2\right|}{26}=\frac{4}{13}\)
\(\Leftrightarrow\left|x+2\right|.13=4.26\)
\(\Leftrightarrow\left|x+2\right|.13=104\)
\(\Leftrightarrow\left|x+2\right|=8\)
\(\Leftrightarrow\orbr{\begin{cases}x+2=8\\x+2=-8\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=6\\x=-10\end{cases}}\)
Vậy x = 6 hoặc x = -10
\(4,x-\left(1\frac{1}{3}-\frac{2}{3}\right)=2\)
\(\Leftrightarrow x-\left(\frac{4}{3}-\frac{2}{3}\right)=2\)
\(\Leftrightarrow x-\frac{2}{3}=2\)
\(\Leftrightarrow x=2+\frac{2}{3}\)
\(\Leftrightarrow x=\frac{8}{3}\)
\(5,\frac{2}{5}:x-\frac{1}{5}=\frac{3}{5}\)
\(\Leftrightarrow\frac{2}{5}:x=\frac{3}{5}+\frac{1}{5}\)
\(\Leftrightarrow\frac{2}{5}:x=\frac{4}{5}\)
\(\Leftrightarrow x=\frac{2}{5}:\frac{4}{5}\)
\(\Rightarrow x=\frac{1}{2}\)
\(6,\frac{1}{2}.\left(3x-\frac{2}{5}\right)=\left(-3\right)^2\)
\(\Leftrightarrow\frac{1}{2}.\left(3x-\frac{2}{5}\right)=9\)
\(\Leftrightarrow3x-\frac{2}{5}=9:\frac{1}{2}\)
\(\Leftrightarrow3x-\frac{2}{5}=18\)
\(\Leftrightarrow3x=\frac{92}{5}\)
\(\Leftrightarrow x=\frac{92}{5}:3\)
\(\Rightarrow x=\frac{92}{15}\)
\(\frac{-x}{15}=\frac{10}{25}\)
\(\Leftrightarrow25\times\left(-x\right)=10\times15\)
\(-25x=150\)
\(x=150\div\left(-25\right)\)
\(x=-6\)
