Question

[Fenny]

Tìm cá số nguyên x, y biết

a) Ix + 3I + Iy - 1I = 0

b) Ix + 5I + Iy + 1I \(\le\)0

Answer 1

[All For E]

                                                          Bài giải

a, \(\left|x+3\right|+\left|y-1\right|=0\)

Mà \(\hept{\begin{cases}\left|x+3\right|\ge0\forall x\\\left|y-1\right|\ge0\forall x\end{cases}}\Rightarrow\hept{\begin{cases}\left|x+3\right|=0\\\left|y-1\right|=0\end{cases}}\Rightarrow\hept{\begin{cases}x=-3\\y=1\end{cases}}\)

Vậy \(\left(x\text{ ; }y\right)=\left(-3\text{ ; }1\right)\)

b, \(\left|x+5\right|+\left|y+1\right|\le0\)

Mà \(\hept{\begin{cases}\left|x+5\right|\ge0\forall x\\\left|y+1\right|\ge0\end{cases}}\Rightarrow\text{ }\left|x+5\right|+\left|y+1\right|=0\)

Dấu " = " xảy ra khi \(\hept{\begin{cases}\left|x+5\right|=0\\\left|y+1\right|=0\end{cases}}\Rightarrow\hept{\begin{cases}x=-5\\y=-1\end{cases}}\)

Vậy \(\left(x\text{ ; }y\right)=\left(-5\text{ ; }-1\right)\)