Question

\(\dfrac{x}{5}\) = \(\dfrac{y}{4}\) =\(\dfrac{z}{3}\) và x + y - z =18

Answer 1

Áp dụng tcdtsbn , ta có:

\(\dfrac{x}{5}=\dfrac{y}{4}=\dfrac{z}{3}=\dfrac{x+y-z}{5+4-3}=\dfrac{18}{6}=3\)

\(\Rightarrow x=15\)

\(\Rightarrow y=12\)

\(\Rightarrow9\)

Answer 2

Áp dụng TCDTSBN. Ta có:

\(\dfrac{x}{5}=\dfrac{y}{4}=\dfrac{z}{3}=\dfrac{x+y-z}{5+4-3}=\dfrac{18}{6}=3\)

=> \(\left\{{}\begin{matrix}\dfrac{x}{5}=3\Rightarrow x=15\\\dfrac{y}{4}=3\Rightarrow y=12\\\dfrac{z}{3}=3\Rightarrow z=9\end{matrix}\right.\)

 

Answer 3

Áp dụng dãy tỉ số bằng nhau ta có : 

`x/5  =y/4 = z/3 = (x+y-z)/(5+4 - 3) = 18/6=  3`

`x/5 =3 => x = 15`

`y/4 = 3 => x = 12`

`z/3 = 3 => x = 9`