Question

\(x+15\%.x=115\)

\(|x+8|=10\)

\(\frac{4}{x}=\frac{-y}{6}=0.5\)

Answer 1

|x + 8| = 10

=> x + 8 = 10 hoặc  x + 8 = -10

=> x = 2 hoặc x = -18

vậy_

Answer 2

\(x+15\%x=115\)

\(\Leftrightarrow x+\frac{15}{100}x=115\)

\(\Leftrightarrow x+\frac{3}{20}x=115\)

\(\Leftrightarrow x\left(1+\frac{3}{20}\right)=115\)

\(\Leftrightarrow x\left(\frac{20}{20}+\frac{3}{20}\right)=115\)

\(\Leftrightarrow\frac{23}{20}x=115\)

\(\Leftrightarrow x=115\div\frac{23}{20}\)

\(\Leftrightarrow x=115\times\frac{20}{23}\)

\(\Leftrightarrow x=\frac{2300}{23}=100\)

Answer 3

\(\frac{4}{x}=\frac{-y}{6}=0,5\)

\(\Rightarrow\hept{\begin{cases}\frac{4}{x}=0,5\Leftrightarrow x=8\\\frac{-y}{6}=0,5\Leftrightarrow y=-3\end{cases}}\)

Vậy \(\left(x,y\right)\in\left\{\left(8,-3\right)\right\}\)