a: Để A=1/2 thì \(\dfrac{1}{2}\left|5-3x\right|=\dfrac{1}{2}+\dfrac{1}{3}=\dfrac{5}{6}\)
=>|3x-5|=5/3
=>3x-5=5/3 hoặc 3x-5=-5/3
=>3x=20/3 hoặc 3x=10/3
=>x=20/9 hoặc x=10/9
b: \(A=\dfrac{1}{2}\left|5-3x\right|-\dfrac{1}{3}>=-\dfrac{1}{3}\)
Dấu = xảy ra khi x=5/3