Question

tìm số nguyên x,y thỏa mãn: xy-x-y-1=0

Answer 1

Ta có : \(xy-x-y-1=0\)

\(\Rightarrow\left(xy-x\right)-y-1=0\)

\(\Rightarrow x\left(y-1\right)-\left(y-1\right)-2=0\)

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

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

\(\Rightarrow y-1;x-1\inƯ\left(2\right)=\left\{\pm1;\pm2\right\}\)

Ta có bảng sau :

\(y-1\)	\(1\)	\(2\)	\(-1\)	\(-2\)
\(x-1\)	\(2\)	\(1\)	\(-2\)	\(-1\)
\(x\)	\(3\)	\(2\)	\(-1\)	\(0\)
\(y\)	\(2\)	\(3\)	\(0\)	\(-1\)

Vậy \(\left(x;y\right)\in\left\{\left(3;2\right),\left(2;3\right),\left(-1;0\right),\left(0;-1\right)\right\}\)  

Answer 2

Xy-x-y-5=4 nhanh giùm mìnhĐang cần gấp