Bài 1:
Ta thấy: \(\left\{\begin{matrix}a^2\ge0\\b^2\ge0\end{matrix}\right.\)\(\Rightarrow\left\{\begin{matrix}-a^2\le0\\-b^2\le0\end{matrix}\right.\)
\(\Rightarrow-a^2-b^2\le0\)
\(\Rightarrow Q\le0\)
Dấu "=" xảy ra khi \(\left\{\begin{matrix}-a^2=0\\-b^2=0\end{matrix}\right.\)\(\Rightarrow\left\{\begin{matrix}a^2=0\\b^2=0\end{matrix}\right.\)\(\Rightarrow a=b=0\)
Vậy \(Max_Q=0\) khi a=b=0
Bài 2:
Ta thấy: \(\left\{\begin{matrix}x^2\ge0\\y^2\ge0\end{matrix}\right.\)
\(\Rightarrow x^2+y^2\ge0\)
\(\Rightarrow P\ge0\)
Dấu "=" xảy ra khi \(\left\{\begin{matrix}x^2=0\\y^2=0\end{matrix}\right.\)\(\Rightarrow x=y=0\)
Vậy \(Min_P=0\) khi x=y=0
