Question

Cho (x - y):( x + y) : xy = 1:7:24 ( xy khác 0).Tính xy

Hu hu các bn giúp mk nha mk sắp thi rùi!

Answer 1

\(baira\Rightarrow\dfrac{x-y}{1}=\dfrac{x+y}{7}=\dfrac{xy}{24}\) (1) va x,y \(\ne0\).

\(\Rightarrow\) \(\dfrac{x-y}{1}=\dfrac{x+y}{7}=\dfrac{x-y+x+y}{1+7}=\dfrac{x}{4}=\dfrac{x-y-\left(x+y\right)}{1-7}=\dfrac{y}{3}\) (2)

từ (1) và (2) \(\Rightarrow\) \(\dfrac{x}{4}=\dfrac{xy}{24}\Rightarrow\dfrac{x}{4}-\dfrac{xy}{24}=x\left(\dfrac{1}{4}-\dfrac{y}{24}\right)=0\)

vì x\(\ne\)0 \(\Rightarrow\)\(\dfrac{1}{4}-\dfrac{y}{24}=0\Rightarrow y=\dfrac{24}{4}=6\)

thay y=6 vao \(\dfrac{x}{4}=\dfrac{y}{3}\Rightarrow x=4\times\dfrac{y}{3}=4\times\dfrac{6}{3}=8\)

vậy x.y= 8.6 = 48

Answer 2

x=4, y=3