Question

\(\dfrac{x}{19}=\dfrac{y}{21}và2x-y=34\)

Answer 1

Áp dụng t/c dtsbn:

\(\dfrac{x}{19}=\dfrac{y}{21}=\dfrac{2x-y}{19\cdot2-21}=\dfrac{34}{17}=2\\ \Rightarrow\left\{{}\begin{matrix}x=38\\y=42\end{matrix}\right.\)

Answer 2

\(\dfrac{2x}{19.2}=\dfrac{y}{21}\) và \(\text{ 2x− y = 34}\)

Áp dụng tcdtsbn , ta có:

\(\dfrac{2x}{19.2}=\dfrac{y}{21}=\dfrac{2x-y}{19.2-21}=\dfrac{34}{17}=2\)

\(\Rightarrow x=76\)

\(\Rightarrow y=42\)

 

Answer 3

Ta có: \(\dfrac{x}{19}=\dfrac{y}{21}=\dfrac{2x}{38}=\dfrac{y}{21}\)

Áp dụng tính chất dãy tỉ số bằng nhau, ta được:

\(\dfrac{2x+y}{38+21}=\dfrac{34}{59}\)

=> \(\left\{{}\begin{matrix}x=10,94...\\y=12,101...\end{matrix}\right.\)