Question

a/\(1\frac{1}{2}.X-0,5.X+20\%.X=31\)

B/\(\frac{X-2}{7}=\frac{-7}{2-X}\)

Answer 1

a, \(1\frac{1}{2}.x-0,5x+20\%x=31\)

\(\frac{3}{2}x-\frac{1}{2}x+\frac{1}{5}x=31\)

\(x\left(\frac{3}{2}-\frac{1}{2}+\frac{1}{5}\right)=31\)

\(x.\frac{6}{5}=31\)

\(x=\frac{155}{6}\)

Answer 2

b, \(\frac{x-2}{7}=\frac{-7}{2-x}\)

\(\Rightarrow\frac{x-2}{7}=\frac{-7}{-\left(x-2\right)}\)

\(\Rightarrow-\left(x-2\right)\left(x-2\right)=7.\left(-7\right)=-49\)

\(\Rightarrow\left(x-2\right)^2=49=7^2\)

\(\Rightarrow\orbr{\begin{cases}x-2=7\\x-2=-7\end{cases}\Rightarrow}\orbr{\begin{cases}x=9\\x=-5\end{cases}}\)