Question

[Do minh linh trang]

\(a.\frac{x-1}{x+2}=\frac{4}{5}\left(x\ne-2\right)\)                                                    e)\(\frac{x}{-8}=\frac{2}{-x^3}\left(x\ne0\right)\)

b)\(\frac{1}{12}:\frac{4}{21}=3\frac{1}{2}:\left(3x-2\right)\)                                               F)\(\frac{x}{8}=\frac{x}{x^3}\left(x\ne0\right)\)

c)\(\frac{x^2}{-8}=\frac{27}{x}\left(x\ne0\right)\)

d)\(\frac{x+7}{-20}=\frac{-5}{x+7}\left(x\ne-7\right)\)

Answer 1

[Khánh Ngọc]

\(a.\frac{x-1}{x+2}=\frac{4}{5}\)

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

\(\Rightarrow1-\frac{3}{x+2}=\frac{4}{5}\)

\(\Rightarrow\frac{3}{x+2}=1-\frac{4}{5}\)

\(\Rightarrow\frac{3}{x+2}=\frac{1}{5}\)

\(\Rightarrow\frac{3}{x+2}=\frac{3}{15}\Rightarrow x+2=15\)

\(\Rightarrow x=13\)( thỏa mãn )