Question

Có tất cả bao nhiêu cặp số nguyên (x, y) thỏa mãn: |x| + |y| = 1

Answer 1

\(\left|x\right|+\left|y\right|=1=0+1\)

TH1: \(\left\{{}\begin{matrix}\left|x\right|=0\\\left|y\right|=1\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=0\\y=\pm1\end{matrix}\right.\)

TH2: \(\left\{{}\begin{matrix}\left|x\right|=1\\\left|y\right|=0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=\pm1\\y=0\end{matrix}\right.\)

Answer 2

Có 2 cặp

Answer 3

Ta có: |x|+|y|=1

nên \(\left(\left|x\right|,\left|y\right|\right)\in\left\{\left(0;1\right);\left(1;0\right)\right\}\)

\(\Leftrightarrow\left(x,y\right)\in\left\{\left(0;-1\right);\left(0;1\right);\left(-1;0\right);\left(1;0\right)\right\}\)