Question

tìm x, y nguyên biết: xy +3x-y=6

Answer 1

\(xy+3x-y=6\\ \Rightarrow x\left(y+3\right)-y-3=3\\ \Rightarrow x\left(y+3\right)-\left(y+3\right)=3\\ \Rightarrow\left(x-1\right)\left(y+3\right)=3\)

Ta có bảng:

x-1	-1	-3	1	3
y+3	-3	-1	3	1
x	0	-2	2	4
y	-6	-4	0	-2

 

Vậy\(\left(x,y\right)\in\left\{\left(0;-6\right);\left(-2;-4\right);\left(2;0\right);\left(4;-2\right)\right\}\)