Question

Tìm các số x,y biết : x + y = x . y = x : y

Answer 1

\(x.y=x\div y\) nên \(x.y\div\frac{x}{y}=1\)hay \(\frac{x.y.y}{x}=y^2=1\)

Vậy \(y=1\)hoặc \(-1\)

\(\Rightarrow\left[\begin{matrix}y=1\Rightarrow\frac{1}{x}=1-1=0\left(loai\right)\\y=-1\Rightarrow\frac{1}{x}=1-\left(-1\right)=2\Rightarrow x=\frac{1}{2}\end{matrix}\right.\)

\(\Rightarrow x=\frac{1}{2};y=-1\)

Answer 2

x.y=x:y=> x.y:\(\frac{x}{y}\)=1=>y²=1=> y=-1 hoặc y=1

Answer 3

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