a: x<-0,8
=>x+0,8<=0
=>x+0,8-3,3<=-3,3<0
=>x-2,5<=0
\(A=\left|x+0,8\right|-\left|x-2,5\right|+1,9\)
=-x-0,8-(2,5-x)+1,9
=-x-0,8-2,5+x+1,9
=-3,3+1,9
=-1,4
b: \(\dfrac{2}{3}< =x< =4,1\)
=>\(x-\dfrac{2}{3}>=0;x-4,1< =0\)
=>\(\left|x-\dfrac{2}{3}\right|=x-\dfrac{2}{3};\left|x-4,1\right|=4,1-x\)
\(B=\left|x-4,1\right|+\left|x-\dfrac{2}{3}\right|-9\)
\(=4,1-x+x-\dfrac{2}{3}-9\)
\(=-4,9-\dfrac{2}{3}=-\dfrac{49}{10}-\dfrac{2}{3}=\dfrac{-147-20}{30}=-\dfrac{167}{30}\)
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