Bài 1:
Áp dụng tính chất dãy tỉ số bằng nhau ta có:
\(\dfrac{3x-2y}{4}=\dfrac{2z-4x}{3}=\dfrac{4y-3z}{2}=\dfrac{12x-8y+6z-12x+8y-6z}{16+9+4}=\dfrac{0}{29}=0\)
\(\Rightarrow\left\{{}\begin{matrix}3x-2y=0\Rightarrow3x=2y\Rightarrow\dfrac{x}{2}=\dfrac{y}{3}\\2z-4x=0\Rightarrow2z=4x\Rightarrow\dfrac{x}{2}=\dfrac{z}{4}\end{matrix}\right.\)
\(\Rightarrow\dfrac{x}{2}=\dfrac{y}{3}=\dfrac{z}{4}\)
Áp dụng tính chất dãy tỉ số bằng nhau ta có:
\(\dfrac{x}{2}=\dfrac{y}{3}=\dfrac{z}{4}=\dfrac{x+y+z}{2+3+4}=\dfrac{18}{9}=2\)
\(\Rightarrow\left\{{}\begin{matrix}x=4\\y=6\\z=8\end{matrix}\right.\)
Vậy \(x=4;y=6;z=8\)
Bài 2:
Áp dụng tính chất dãy tỉ số bằng nhau ta có:
\(\dfrac{2bz-3cy}{a}=\dfrac{3cx-az}{2b}=\dfrac{ay-2bx}{3c}=\dfrac{2abz-3acy+6bcx-2baz+3cay-6bcx}{a^2+4b^2+9c^2}\)
\(\Rightarrow\left\{{}\begin{matrix}2bz-3cy=0\Rightarrow2bz=3cy\Rightarrow\dfrac{y}{2b}=\dfrac{z}{3c}\\3cx-az=0\Rightarrow3cx=az\Rightarrow\dfrac{x}{a}=\dfrac{z}{3c}\end{matrix}\right.\)
\(\Rightarrow\dfrac{x}{a}=\dfrac{y}{2b}=\dfrac{z}{3c}\left(đpcm\right)\)
Vậy \(\dfrac{x}{a}=\dfrac{y}{2b}=\dfrac{z}{3c}\)
