Đặt A = |3 - x| + 4
Ta có: \(\left|3-x\right|\ge0\)
\(\Rightarrow\left|3-x\right|+4\ge4\)
\(\Rightarrow A\ge4\)
Dấu '=' xảy ra khi x = 3
Vậy AMin = 4 khi x = 3
Đặt \(\left|3-x\right|+4\)
Ta có: \(\left|3-x\right|\ge0\)
\(\Rightarrow\left|3-x\right|+4\ge4\)
\(\Rightarrow A\ge4\)
Dấu '=' xảy ra khi x = 3
\(\Rightarrow A_{Min}=4\)khi x = 3
Ta thấy \(\left|3-x\right|\ge4\)
Gọi \(\left|3-x\right|+4=P\)
Ta có : \(\left|3-x\right|+4\ge0+4\ge4\)
\(A_{min}=4\Leftrightarrow3-x=0\Rightarrow x=3\)