\(\Leftrightarrow\left(x-1;y-2\right)\in\left\{\left(1;6\right);\left(2;3\right);\left(3;2\right);\left(6;1\right);\left(-1;-6\right);\left(-2;-3\right);\left(-3;-2\right);\left(-6;-1\right)\right\}\)
hay \(\left(x,y\right)\in\left\{\left(6;8\right);\left(3;5\right);\left(4;4\right);\left(7;3\right)\right\}\)
\(b)(x-1)(y-2)=6\)
\(<=>(x-1)(y-2)+6=0\)
\(<=>xy-2x-y+2+6=0\)
\(<=>(xy-y)+(2x-2)+6=0\)
\(<=>y(x-1)+2(x-1)+6=0\)
\(<=>(x-1)(y+2+6)=0\)
\(<=>[(x-1)=0<=>[x=1\)
\(<=>[(y+2+6)=0<=>[x=-8\)
(x-1).(y-2)=6
x = 6 - 2 - 1
x = 3
y = 6 : 2 -1
y = 2
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