Question

2) Tìm các số nguyên thỏa mãn: x. (y + 1) + y = 12

Answer 1

=>xy+x+y=12

=>y(x+1)+x+1=13

=>(x+1)(y+1)=13

=>\(\left(x+1;y+1\right)\in\left\{\left(1;13\right);\left(13;1\right);\left(-1;-13\right);\left(-13;-1\right)\right\}\)

=>\(\left(x,y\right)\in\left\{\left(0;12\right);\left(12;0\right);\left(-2;-14\right);\left(-14;-2\right)\right\}\)