ta có
\(N=\frac{5x-3y}{2x+y}=\frac{\frac{5x}{y}-\frac{3y}{y}}{\frac{2x}{y}+\frac{y}{y}}=\frac{\frac{5}{2}-3}{\frac{2}{2}+1}=-\frac{1}{4}\)
\(\frac{x}{y}=\frac{1}{2}\Rightarrow\hept{\begin{cases}2x=y\\5x=\frac{5}{2}y\end{cases}}\)
\(N=\frac{5x-3y}{2x+y}=\frac{\frac{5}{2}y-3y}{y+y}=\frac{-\frac{1}{2}y}{2y}=-\frac{1}{4}\)
Ta có : \(\frac{x}{y}=\frac{1}{2}\Leftrightarrow\frac{x}{1}=\frac{y}{2}\)Đặt \(x=k;y=2k\)
hay \(N=\frac{5k-6k}{2k+2k}=\frac{-k}{4k}=-\frac{1}{4}\)
Vậy N = -1/4 khi x/y = 1/2