Question

Tìm các số x,y,z thỏa mãn x:y:z=3:5:(-2) và 5x - y+3z =-16

Answer 1

giúp

 

Answer 2

Ta có: x:y:z=3:5:(-2)= \(\dfrac{5x}{15}\):\(\dfrac{y}{5}:\dfrac{3z}{-6}\)

\(\dfrac{5x-y+3z}{15-5+\left(-6\right)}=-\dfrac{16}{4}=-4\)

\(\dfrac{x}{3}=-4\Rightarrow x=-12\)

\(\dfrac{y}{5}=-4\Rightarrow y=-20\)

\(\dfrac{z}{-2}=-4\Rightarrow z=8\)

Answer 3

x:y:z=3:5:(-2)⇒\(\dfrac{x}{3}=\dfrac{y}{5}=\dfrac{z}{-2}\)

Áp dụng tính chất đãy tỉ số bằng nhau ta có:

\(\dfrac{x}{3}=\dfrac{y}{5}=\dfrac{z}{-2}=\dfrac{5x}{15}=\dfrac{y}{5}=\dfrac{3z}{-6}=\dfrac{5x-y+3z}{15-5-6}=-\dfrac{16}{4}=-4\)

\(\dfrac{x}{3}=-4\Rightarrow x=-12\)

\(\dfrac{y}{5}=-4\Rightarrow y=-20\)

\(\dfrac{z}{-2}=-4\Rightarrow z=8\)