3 có à ;-;

B

C

\(A=3\left|1-2x\right|-5\)

Ta có: \(\left|1-2x\right|\ge0\forall x\)

\(\Rightarrow3.\left|1-2x\right|-5\ge-5\forall x\)

\(\Rightarrow A\ge-5\forall x\)

Dấu "=" xảy ra

\(\Leftrightarrow3.\left|1-2x\right|=0\Leftrightarrow1-2x=0\Leftrightarrow x=\dfrac{1}{2}\)

\(B=80^0\)

\(\dfrac{2}{3}+\dfrac{1}{12}=\dfrac{8}{12}+\dfrac{1}{12}=\dfrac{3}{4}\)