Question

Tìm x , y \(\in\) Z biết

a, xy + 2x + 2y = -16

b, ( x - 3 ) . ( y + 2 ) = 11

c, xy - 3x - y = 0

Answer 1

b: \(\Leftrightarrow\left(x-3;y+2\right)\in\left\{\left(1;11\right);\left(11;1\right);\left(-1;-11\right);\left(-11;-1\right)\right\}\)

hay \(\left(x,y\right)\in\left\{\left(4;9\right);\left(14;-1\right);\left(2;-13\right);\left(-8;-3\right)\right\}\)

c: \(\Leftrightarrow x\left(y-3\right)-y+3=3\)

=>(y-3)(x-1)=3

\(\Leftrightarrow\left(x-1;y-3\right)\in\left\{\left(1;3\right);\left(3;1\right);\left(-1;-3\right);\left(-3;-1\right)\right\}\)

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