Toán Lớp 6: 2 số nguyên x , y biết : x – y + xy -2 = 2
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Toán Lớp 6: 2 số nguyên x , y biết : x – y + xy -2 = 2
Comments ( 2 )
=>(x+xy)-y-2=2
=>x.(1+y)-y-1-1=2
=>x.(y+1)-(y+1)=2+1
=>(x-1)(y+1)=3
Mà 3=1.3=3.1=(-1).(-3)=(-3).(-1)
Ta có bảng sau:
$\begin{array}{|c|c|}\hline x-1&1&3&-1&-3\\\hline y+1&3&1&-3&-1\\\hline x&2&4&0&-2\\\hline y&2&0&-4&-2\\\hline\end{array}$
Vậy (x;y)={(2;2);(4;0);(0;-4);(-2;-2)}