2) Ta có:
\(\dfrac{1}{2}x=\dfrac{3}{4}y=\dfrac{2}{3}z\)
\(\Rightarrow12\cdot\dfrac{1}{2}x=12\cdot\dfrac{3}{4}y=12\cdot\dfrac{2}{3}z\)
\(\Rightarrow6x=9y=8z\)
\(\Rightarrow\dfrac{6x}{72}=\dfrac{9y}{72}=\dfrac{8z}{72}\)
\(\Rightarrow\dfrac{x}{12}=\dfrac{y}{8}=\dfrac{z}{9}\)
Mà: \(2x-3y+z=9\)
Áp dụng tính chất dãy tỉ số bằng nhau ta có:
\(\dfrac{x}{12}=\dfrac{y}{8}=\dfrac{z}{9}=\dfrac{2x-3y+z}{2\cdot12-3\cdot8+9}=\dfrac{9}{9}=1\)
\(\Rightarrow\dfrac{x}{12}=1\Rightarrow x=12\)
\(\Rightarrow\dfrac{y}{8}=1\Rightarrow y=8\)
\(\Rightarrow\dfrac{z}{9}=1\Rightarrow z=9\)
Đúng 2
Bình luận (0)
