Đáp án:
Giải thích các bước giải:
Bài 10
a) $(x-1)(y-4)=5\\\Leftrightarrow \left[\begin{array}{l}\left\{\begin{array}{l}x-1=-1\\y-4=-5\end{array}\right.\\\left\{\begin{array}{l}x-1=1\\y-4=5\end{array}\right.\end{array}\right.\\\Leftrightarrow (x; y)=\{(0; -1); (2; 9)\}$
b) $x-xy-y=6\\\Leftrightarrow x(1-y)-y=6\\\Leftrightarrow x=\frac{y+6}{1-y}\\\Leftrightarrow y+6\vdots 1-y\\\Leftrightarrow -(1-y)+7\vdots 1-y\\\Leftrightarrow 7\vdots 1-y\\\Leftrightarrow y\in \{2; 0; 8; -6\}\\\Rightarrow (x; y)=\{(-8; 2); (6; 0); (-2; 8); (0; -6)\}$