\(\dfrac{x}{4}=\dfrac{y}{5}=\dfrac{x+y}{4+5}=\dfrac{-36}{9}=-4\\ \Rightarrow\left\{{}\begin{matrix}x=-16\\y=-20\end{matrix}\right.\\ \dfrac{x}{y}=\dfrac{7}{13}\Rightarrow\dfrac{x}{7}=\dfrac{y}{13}=\dfrac{x+y}{7+13}=\dfrac{40}{20}=2\\ \Rightarrow\left\{{}\begin{matrix}x=14\\y=26\end{matrix}\right.\\ \dfrac{x}{35}=\dfrac{y}{50}=\dfrac{2x-y}{2\cdot35-50}=\dfrac{-40}{20}=-2\\ \Rightarrow\left\{{}\begin{matrix}x=-70\\y=-100\end{matrix}\right.\)
1, Áp dụng tcdtsbn , ta có :
\(\dfrac{x}{4}=\dfrac{y}{5}=\dfrac{x+y}{4+5}=\dfrac{-36}{9}=-4\)
\(\Rightarrow\left[{}\begin{matrix}x=-16\\y=-20\end{matrix}\right.\)
2,Ta có: \(\dfrac{x}{y}=\dfrac{7}{13}=\dfrac{x}{7}=\dfrac{y}{13};x+y=40\)
Áp dung tcdtsbn , ta có:
\(\dfrac{x}{7}=\dfrac{y}{13}=\dfrac{x+y}{20}=\dfrac{40}{20}=20\)
\(\Rightarrow\left[{}\begin{matrix}x=140\\y=260\end{matrix}\right.\)
3, Ta có:
\(\dfrac{x}{35}=\dfrac{y}{50}=\dfrac{2x}{2.35}=\dfrac{y}{50}=\dfrac{2x}{70}=\dfrac{y}{50}\)
Áp dụng tcdtsbn , ta có:
\(\dfrac{y}{50}=\dfrac{2x}{70}=\dfrac{2x-y}{70-50}=\dfrac{-40}{20}=-20\)
\(\Rightarrow\left[{}\begin{matrix}x=-700\\y=-1000\end{matrix}\right.\)
