Question

15x = 5y = 3z và 2x - y - z = -18

Answer 1

\(15x=5y=3z\)

\(\Leftrightarrow\dfrac{x}{2}=\dfrac{y}{6}=\dfrac{z}{10}\)

\(\Leftrightarrow\dfrac{2x}{4}=\dfrac{y}{6}=\dfrac{z}{10}=\dfrac{2x-y-z}{4-6-10}=\dfrac{3}{2}\)(t/c dãy tỉ số bằng nhau)

=> \(\left\{{}\begin{matrix}x=3\\y=9\\z=15\end{matrix}\right.\)