\(\dfrac{x}{5}=\dfrac{y}{3};\dfrac{y}{2}=\dfrac{z}{7}\)
\(\Rightarrow\dfrac{x}{10}=\dfrac{y}{6};\dfrac{y}{6}=\dfrac{z}{21}\)
\(\Rightarrow\dfrac{x}{10}=\dfrac{y}{6}=\dfrac{z}{21}\)
\(\Rightarrow\dfrac{5x}{50}=\dfrac{y}{6}=\dfrac{2z}{42}\)
Dựa vào tính chất dãy tỉ số bằng nhau ta có:
\(\dfrac{5x}{50}=\dfrac{y}{6}=\dfrac{2z}{42}\)
\(=\dfrac{5x+y-2z}{50+6-42}\)
\(=\dfrac{28}{14}=2\)
\(\Rightarrow\left\{{}\begin{matrix}x=2.10=20\\y=2.6=12\\z=2.21=42\end{matrix}\right.\)
- Theo đề bài ta có:
\(\dfrac{x}{5}=\dfrac{y}{3},\dfrac{y}{2}=\dfrac{z}{7}\)
=> \(\dfrac{x}{10}=\dfrac{y}{6}=\dfrac{z}{21}\)
- Áp dụng tính chất của dãy tỉ số bằng nhau ta có:
\(\dfrac{x}{10}=\dfrac{y}{6}=\dfrac{z}{21}\)=\(\dfrac{5x}{50}\)=\(\dfrac{2z}{42}\)
=\(\dfrac{5x+y-2z}{50+6-42}\)=\(\dfrac{28}{14}=2\)
- Suy ra:
x=2*10=20
y=2*6=12
z=2*21=42.
- Vậy
x=20
y=12
z=42.