1) Ư(5)={1; -1; 5; -5};
Ư(-30)={\(\pm1;\pm2;\pm3;\pm5;\pm6;\pm10;\pm15;\pm30\)}
Ư(19)={\(\pm1;\pm19\)}
Ư(22)=\(\left\{\pm1;\pm2;\pm11;\pm22\right\}\)
2b)BCNN(-8; -4)={8}
a)B(-8)={\(\pm8;\pm16;\pm24;\pm32;\pm40;...\)}
B(-4)\(\left\{\pm4;\pm8;\pm12;\pm16;\pm20;...\right\}\)