Question

Tìm x,y E Z biết

a, (x-1)(y+1) = 5

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

c, xy + 3x - 7y = 21

d, /x-8/ + /y+2/ = 2

Giúp mk nha

Thks

Answer 1

a: (x-1)(y+1)=5

\(\Leftrightarrow\left(x-1;y+1\right)\in\left\{\left(1;5\right);\left(5;1\right);\left(-1;-5\right);\left(-5;-1\right)\right\}\)

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

b: (x+2)(y-3)=-3

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

hay \(\left(x,y\right)\in\left\{\left(-1;0\right);\left(-5;4\right);\left(-3;6\right);\left(1;2\right)\right\}\)