Question

[dgsdsd]

Tìm x,y,z biết : \(\frac{x}{y}=\frac{10}{9};\frac{y}{z}=\frac{3}{4}\)  và x - y + z = 78

Answer 1

[Thanh Tùng DZ]

\(\frac{x}{y}=\frac{10}{9}\text{ }\Rightarrow\text{ }\frac{x}{10}=\frac{y}{9}\text{ }\left(1\right)\)

\(\frac{y}{z}=\frac{3}{4}=\frac{9}{12}\text{ }\Rightarrow\text{ }\frac{y}{9}=\frac{z}{12}\text{ }\left(2\right)\)

Từ ( 1 ) và ( 2 ) suy ra : \(\frac{x}{10}=\frac{y}{9}=\frac{z}{12}=\frac{x-y+z}{10-9+12}=\frac{78}{13}=6\)

Do đó : x = 6 . 10 = 60 ; y = 6 . 9 = 54 ' z = 6 . 12 = 72

Answer 2

[Nguyễn Thị Ngố]

Ta có: \(\frac{x}{y}=\frac{10}{9}\) và \(\frac{y}{z}=\frac{3}{4}\)

=> \(\frac{y}{z}=\frac{9}{12}\) 

=> \(\frac{x}{10}=\frac{y}{9}=\frac{z}{12}\)

=> \(\frac{x}{10}=\frac{y}{9}=\frac{z}{12}=\frac{x-y+z}{10-9+12}=\frac{87}{13}=6\)

=>\(\frac{x}{10}=6=>x=60\) ; \(\frac{y}{9}=6=>y=54\); \(\frac{z}{12}=6=>z=72\)

vậy x=60 ; y=54 ; z=72