Question

Answer 1

Ta có: \(\dfrac{5}{x}+\dfrac{y}{4}=\dfrac{1}{8}\)

\(\Rightarrow\dfrac{5}{x}=\dfrac{1}{8}-\dfrac{y}{4}\)

\(\Rightarrow\dfrac{5}{x}=\dfrac{1}{8}-\dfrac{2y}{8}\)

\(\Rightarrow\dfrac{5}{x}=\dfrac{1-2y}{8}\)

\(\Rightarrow x\cdot\left(1-2y\right)=40\)

Xét ta có: \(1-2y\) lẻ với mọi y

Mà: Ư(40)=\(\left\{\pm1;\pm2;\pm4;\pm5;\pm8;\pm10;\pm20;\pm40\right\}\)

\(\Rightarrow1-2y\in\left\{\pm1;\pm5\right\}\) 

\(1-2y\)	-1	1	5	-5
\(x\)	-40	40	8	-8
\(y\)	1	0	-2	3

Vậy: ...