Đáp án+giải thích các bước giải:
xy - 2x = 19
⇒x(y-2)=19
Vì x,y ∈ Z ⇒ x , y-2 ∈ Z
⇒ x , y-2 ∈ Ư (19) ∈ {-1,1,-19,19}
TH1:
\(\left[ \begin{array}{l}x=1\\y-2=19\end{array} \right.\) =\(\left[ \begin{array}{l}x=1\\y=21\end{array} \right.\)
TH2:
\(\left[ \begin{array}{l}x=19\\y-2=1\end{array} \right.\)= \(\left[ \begin{array}{l}x=19\\y=3\end{array} \right.\)
TH3:
\(\left[ \begin{array}{l}x=-1\\y-2=-19\end{array} \right.\) =\(\left[ \begin{array}{l}x=-1\\y=-17\end{array} \right.\)
TH4:
\(\left[ \begin{array}{l}x=-19\\y-2=-1\end{array} \right.\)= \(\left[ \begin{array}{l}x=-19\\y=1\end{array} \right.\)
