Question

\(\dfrac{x}{7}=\dfrac{y}{9}=\dfrac{z}{11}vày-x=-1\)

Answer 1

\(\dfrac{x}{7}=\dfrac{y}{9}=\dfrac{z}{11}\)

Áp dụng tính chất của dãy tỉ sô bằng nhau ta có :

\(\dfrac{x}{7}=\dfrac{y}{9}=\dfrac{z}{11}=\dfrac{y-x}{9-7}=\dfrac{-1}{2}\)

\(\Rightarrow\left\{{}\begin{matrix}\dfrac{x}{7}=\dfrac{-1}{2}\\\dfrac{y}{9}=\dfrac{-1}{2}\\\dfrac{z}{11}=\dfrac{-1}{2}\end{matrix}\right.\)

\(\Rightarrow\left\{{}\begin{matrix}x=\dfrac{-7}{2}\\y=\dfrac{-9}{2}\\z=\dfrac{-11}{2}\end{matrix}\right.\)

Answer 2

Ta có : \(\dfrac{x}{7}=\dfrac{y}{9}=\dfrac{z}{11}\)

Áp dụng tính chất dãy tỉ số bằng nhâu , ta có:

\(\dfrac{x}{7}=\dfrac{y}{9}=\dfrac{z}{11}=\dfrac{y-x}{9-7}=-\dfrac{1}{2}\\ \Rightarrow\left\{{}\begin{matrix}x=-\dfrac{1}{2}.7=-\dfrac{7}{2}\\y=-\dfrac{1}{2}.9=-\dfrac{9}{2}\\z=-\dfrac{1}{2}.11=-\dfrac{11}{2}\end{matrix}\right.\)

Vậy \(x=-\dfrac{7}{2}\); \(y=-\dfrac{9}{2}\); \(z=-\dfrac{11}{2}\)