a) \(\left|x-3\right|\ge0\)
\(\Rightarrow\left|x-3\right|+2021\ge2021\)
\(\Rightarrow A\ge\dfrac{2020}{2021}\)
Dấu = xảy ra khi x = 3
Vậy:............
b) Ta có: \(\left\{{}\begin{matrix}\left(x-\dfrac{3}{5}\right)^2\ge0\\\left|y+1\right|\ge0\end{matrix}\right.\)
PT => \(\left\{{}\begin{matrix}x=\dfrac{3}{5}\\y=-1\end{matrix}\right.\)