Question

tìm x,y,z biết : \(\frac{x}{2}=\frac{y}{3},\frac{y}{5}=\frac{z}{4}\) và x-y+z = -21

mình cần gấp

Answer 1

\(\frac{x}{2}=\frac{y}{3}\Rightarrow\frac{x}{10}=\frac{y}{15}\)

\(\frac{y}{5}=\frac{z}{4}\Rightarrow\frac{y}{15}=\frac{z}{12}\)

\(\Rightarrow\frac{x}{10}=\frac{y}{15}=\frac{z}{12}\)

\(\Rightarrow\frac{x-y+z}{10-15+12}=\frac{x}{10}=\frac{y}{15}=\frac{z}{12}\) mà x - y + z = -21

\(\Rightarrow\frac{-21}{7}=\frac{x}{10}=\frac{y}{15}=\frac{z}{12}\)

\(\Rightarrow-3=\frac{x}{10}=\frac{y}{15}=\frac{z}{12}\)

\(\Rightarrow\hept{\begin{cases}x=-3\cdot10=-30\\y=-3\cdot15=-45\\z=-3\cdot12=-36\end{cases}}\)