Toán Lớp 6: Tìm các số nguyên x, y biết: xy – x + 3y – 2 = 6
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Toán Lớp 6: Tìm các số nguyên x, y biết: xy – x + 3y – 2 = 6
Comments ( 2 )
=>x.(y-1)+3y-2=1+5
=>x.(y-1)+3y-2-1=5
=>x.(y-1)+3y-3=5
=>x.(y-1)+3.(y-1)=5
=>(x+3).(y-1)=5
Ta có:
5=1.5=5.1=(-1).(-5)=(-5).(-1)
Ta có bảng sau:
$\begin{array}{|c|c|}\hline x+3&1&5&-1&-5\\\hline y-1&5&1&-5&-1\\\hline x&-2&2&-4&-8\\\hline y&6&2&-4&0\\\hline\end{array}$
Vậy (x;y)\in{(-2;6);(2;2);(-4;-4);(-8;0)}