Bài 6:
\(max_{x-y}=max_x-min_y=11-\left(-89\right)=100\\ min_{x-y}=min_x-max_y=-2-1=-3\)
Bài 7:
\(\Leftrightarrow2\left(a+b+c\right)=11-3-2=6\\ \Leftrightarrow a+b+c=3\\ \Leftrightarrow\left\{{}\begin{matrix}a=3-\left(b+c\right)=6\\b=11-a=5\\c=-3-b=-8\end{matrix}\right.\)
Bài 7:
Ta có:
\(\left(a+b\right)+\left(b+c\right)+\left(a+c\right)=11+\left(-3\right)+\left(-2\right)\\ \Rightarrow2\left(a+b+c\right)=6\\ \Rightarrow a+b+c=3\)
\(\Rightarrow\left\{{}\begin{matrix}a=\left(a+b+c\right)-\left(b+c\right)=3-\left(-3\right)=6\\b=\left(a+b+c\right)-\left(a+c\right)=3-\left(-2\right)=5\\c=\left(a+b+c\right)-\left(a+b\right)=3-11=-8\end{matrix}\right.\)
Bài 7
Ta có: \(a+b=11;b+c=-3;a+c=-2\)
\(\Rightarrow a+b+b+c+c+a=11+\left(-3\right)+\left(-2\right)\)
\(\Rightarrow2\left(a+b+c\right)=6\)
\(\Rightarrow a+b+c=3\)
Thay a+b=11 vào a+b+c=3 ta có:
\(11+c=3\Rightarrow c=-8\)
Thay b+c=-3 vào a+b+c=3 ta có:
\(\Rightarrow a+\left(-3\right)=3\Rightarrow a=6\)
Thay a=6 và a+b=11 ta có:
\(6+b=11\Rightarrow b=5\)