Bài 3:
a: \(A=-2\left|1-x\right|+3\le3\forall x\)
Dấu '=' xảy ra khi x=1
b: \(B=-2021\left|x-7\right|+2021\le2021\forall x\)
Dấu '=' xảy ra khi x=7
Bài 2:
a) \(M=5\left|x-3\right|+1\ge1\)
\(minM=1\Leftrightarrow x=3\)
b) \(N=\dfrac{1}{2}\left|2x+4\right|+15\ge15\)
\(minN=15\Leftrightarrow x=-2\)
Bài 3:
a) \(A=3-2\left|1-x\right|\le3\)
\(maxA=3\Leftrightarrow x=1\)
b) \(B=2021-2021\left|x-7\right|\le2021\)
\(maxB=2021\Leftrightarrow x=7\)