Ta có:
a) A = |x - 2| + |x - 4| + 2017|
=> A = |x - 2| + |4 - x| + 2017 \(\ge\)|x - 2 + 4 - x| + 2017 = |2| + 2017=2019
Dấu "=" xảy ra <=> (x - 2)(4 - x) \(\ge\)0
<=> 2 \(\le\)x \(\le\)4
Vậy MinA = 2019 <=> 2 \(\le\)x \(\)4
b) Ta có: B = |2019 - x| + |2020 - x|
=> B = |x - 2019| + |2020 - x| \(\ge\)|x - 2019 + 2020 - x| = |1| = 1
Dấu "=" xảy ra <=> (x - 2019)(2020 - x) \(\ge\)0
<=> 2019 \(\le\)x \(\le\)2020
Vậy MinB = 1 <=> 2019 \(\le\)x \(\le\)2020
ta có
/x-2/> hoặc= x-2
/x-4/= /4-x/> hoặc=4-x
=> /x-2/+/x-4/+2017> hoặc= (x-2)+(4-x)+2017=2019
hay A> hoặc= 2019
=> GTNN của A là 2019
b,
Vì /2019-x/ > hoặc= 2019-x
/2020-x/=/x-2020/> hoặc=x-2020
=>/2019-x/+/2020-x/>hoặc=(2019-x)+(x-2020)=-1
Hay B> hoặc=-1
=>B=1
