(x+3)(2y+3)=20
\(\Leftrightarrow\left(x+3;2y+3\right)\in\left\{\left(1;20\right);\left(20;1\right);\left(2;10\right);\left(10;2\right);\left(4;5\right);\left(5;4\right);\left(-1;-20\right);\left(-20;-1\right);\left(-2;-10\right);\left(-10;-2\right);\left(-4;-5\right);\left(-5;-4\right);\right\}\)
\(\Leftrightarrow\left(x,y\right)\in\left\{\left(-2;\dfrac{17}{2}\right);\left(17;-1\right);\left(-1;\dfrac{7}{2}\right);\left(7;-\dfrac{1}{2}\right);\left(1;1\right);\left(2;\dfrac{1}{2}\right);\left(-4;-\dfrac{23}{2}\right);\left(-23;-2\right);\left(-5;-\dfrac{13}{2}\right);;\left(\right)\right\}\)
hoặc \(\left(x,y\right)\in\left\{\left(-13;-\dfrac{5}{2}\right);\left(-7;-4\right);\left(-8;-\dfrac{7}{2}\right)\right\}\)
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