Question

Tìm x,y\(\in\) Z, biết:

a) lx-15l + ly+20l= 0

b) lx+15l + ly-20l=1

Answer 1

a)Ta thấy: \(\left\{\begin{matrix}\left|x-15\right|\ge0\\\left|y+20\right|\ge0\end{matrix}\right.\)

\(\Rightarrow\left|x-15\right|+\left|y+20\right|\ge0\)

Mà \(\left|x-15\right|+\left|y+20\right|=0\)

Xảy ra khi và chỉ khi \(\left\{\begin{matrix}\left|x-15\right|=0\\\left|y+20\right|=0\end{matrix}\right.\)\(\Leftrightarrow\left\{\begin{matrix}x=15\\y=-20\end{matrix}\right.\)

Vậy \(\left\{\begin{matrix}x=15\\y=-20\end{matrix}\right.\)