\(\dfrac{x}{42}=\dfrac{45}{y}=\dfrac{120}{z}=\dfrac{15}{21}\\ \cdot\dfrac{x}{42}=\dfrac{15}{21}\Rightarrow x=\dfrac{42.15}{21}=30\\ \cdot\dfrac{45}{y}=\dfrac{15}{21}\Rightarrow y=\dfrac{45.21}{15}=63\\ \cdot\dfrac{120}{z}=\dfrac{15}{21}\Rightarrow z=\dfrac{120.21}{15}=168\)
Vậy \(x=30;y=63;z=168\)
Ta có: \(\dfrac{x}{42}=\dfrac{45}{y}=\dfrac{120}{z}=\dfrac{15}{21}\)
\(\Leftrightarrow\dfrac{x}{42}=\dfrac{45}{y}=\dfrac{120}{z}=\dfrac{5}{7}\)
\(\Leftrightarrow\left\{{}\begin{matrix}\dfrac{x}{42}=\dfrac{5}{7}\\\dfrac{45}{y}=\dfrac{5}{7}\\\dfrac{120}{z}=\dfrac{5}{7}\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=\dfrac{42\cdot5}{7}=30\\y=\dfrac{45\cdot7}{5}=63\\z=\dfrac{120\cdot7}{5}=168\end{matrix}\right.\)
Vậy: (x,y,z)=(30;63;168)
