Question

Cho A=\(\dfrac{x+2y-3z}{x-2y+3z}\) tính A biết x,y,z tỉ lệ với  5;4;3

Answer 1

\(\dfrac{x}{5}=\dfrac{y}{4}=\dfrac{z}{3}=\dfrac{2y}{8}=\dfrac{3z}{9}=\dfrac{x+2y-3z}{5+8-9}=\dfrac{x-2y+3z}{5-8+9}\\ \Rightarrow A=\dfrac{x+2y-3z}{x-2y+3z}=\dfrac{4}{6}=\dfrac{2}{3}\)