\(\dfrac{x-1}{2}=\dfrac{y-2}{3}=\dfrac{z-3}{4}\) mà \(\dfrac{x-1}{2}=\dfrac{2x-2}{4}\) và \(\dfrac{y-2}{3}=\dfrac{3y-6}{9}\)
=> \(\dfrac{2x-2}{4}=\dfrac{3y-6}{9}=\dfrac{z-3}{4}\) và 2x+3y-z=50
áp dụng tính chất dãy tỉ số bằng nhau ta có
\(\dfrac{2x-2}{4}=\dfrac{3y-6}{9}=\dfrac{z-3}{4}=\dfrac{2x-2+3y-6-z+3}{4+9-4}\) \(=\dfrac{\left(2x+3y-z\right)+\left(-2-6+3\right)}{9}\) \(=\dfrac{50-5}{9}=5\)
\(\dfrac{x-1}{2}=5\Rightarrow x-1=10\Rightarrow x=11\)
\(\dfrac{y-2}{3}=5\Rightarrow y-2=15\Rightarrow y=17\)
\(\dfrac{z-3}{4}=5\Rightarrow z-3=20\Rightarrow z=23\)
Vậy x=11 ; y= 17 ; z=23
Giải:
\(\dfrac{x-1}{2}=\dfrac{y-2}{3}=\dfrac{z-3}{4}\)
\(\Leftrightarrow\dfrac{2\left(x-1\right)}{2.2}=\dfrac{3\left(y-2\right)}{3.3}=\dfrac{z-3}{4}\)
\(\Leftrightarrow\dfrac{2x-2}{4}=\dfrac{3y-6}{9}=\dfrac{z-3}{4}\)
Áp dụng tính chất của dãy tỉ số bằng nhau, ta có:
\(\dfrac{2x-2}{4}=\dfrac{3y-6}{9}=\dfrac{z-3}{4}=\dfrac{2x-2+3y-6-z+3}{4+9-4}=\dfrac{45}{9}=5\)
\(\Leftrightarrow\left\{{}\begin{matrix}2x-2=20\\3y-6=45\\z-3=20\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=\dfrac{20+2}{2}\\y=\dfrac{45+6}{3}\\z=20+3\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=11\\y=17\\z=23\end{matrix}\right.\)
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