Đáp án:
Giải thích các bước giải:
a) Vì 23 chia hết cho x-6⇒ x-6∈Ư(23)={1,23,(-23),(-1)}
\(\left[ \begin{array}{l}x-6=1\\x-6=23\end{array} \right.\) \(\left[ \begin{array}{l}x=7\\x=29\end{array} \right.\)
\(\left[ \begin{array}{l}x-6=-23\\x-6=-1\end{array} \right.\) \(\left[ \begin{array}{l}x=-17\\x=5\end{array} \right.\)
Vậy x∈{7, 29, -17, 5}
b)Vì xy-5y=13
⇒y.(x-5)=13=1.13=13.1=(-1).(-13)=(-13).(-1)
\(\left[ \begin{array}{l}y=1\\x-5=13\end{array} \right.\) \(\left[ \begin{array}{l}y=1\\x=18\end{array} \right.\)
\(\left[ \begin{array}{l}y=13\\x-5=1\end{array} \right.\) \(\left[ \begin{array}{l}y=13\\x=6\end{array} \right.\)
\(\left[ \begin{array}{l}y=-1\\x-5=-13\end{array} \right.\) \(\left[ \begin{array}{l}y=-1\\x=-8\end{array} \right.\)
\(\left[ \begin{array}{l}y=-13\\x-5=-1\end{array} \right.\) \(\left[ \begin{array}{l}y=-13\\x=4\end{array} \right.\)
Vậy (x;y)=(18;1);(6;13);(-8;-1);(4;-13)
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