Question

[Sư Tử Con]

Tìm các STN x , y sao cho :

a) x.( y + 1 ) = 12

b) (3x - 2 ) . ( 2y-3 ) = 1

c) (x+1) (2y-1) =12

Answer 1

[Nguyễn Lê Phước Thịnh]

a: \(\Leftrightarrow\left(x,y+1\right)\in\left\{\left(1;12\right);\left(12;1\right);\left(2;6\right);\left(6;2\right);\left(3;4\right);\left(4;3\right)\right\}\)

hay \(\left(x,y\right)\in\left\{\left(1;11\right);\left(12;0\right);\left(2;5\right);\left(6;1\right);\left(3;3\right);\left(4;2\right)\right\}\)

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

\(\Leftrightarrow\left\{{}\begin{matrix}3x-2=1\\2y-3=1\end{matrix}\right.\Leftrightarrow\left(x,y\right)=\left(1;2\right)\)

c: \(\Leftrightarrow\left(x+1,2y-1\right)\in\left\{\left(12;1\right);\left(4;3\right)\right\}\)

hay \(\left(x,y\right)\in\left\{\left(11;1\right);\left(3;2\right)\right\}\)