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đáp án:

9/27: -2/9 +1/2-3/2= -3/2+ -2/2=-5/2

 K HỘ MK NHA

Ta có :

\(\frac{a}{b+c}=\frac{2a}{2\left(b+c\right)}=\frac{2a}{\left(b+c\right)+b+c}< \frac{2a}{a+b+c}\) 

\(\frac{b}{a+c}=\frac{2b}{2\left(a+c\right)}=\frac{2b}{\left(a+c\right)+a+c}< \frac{2b}{a+b+c}\)

\(\frac{c}{a+b}=\frac{2c}{2\left(a+b\right)}=\frac{2c}{\left(a+b\right)+a+b}< \frac{2c}{a+b+c}\)

\(\frac{\Rightarrow a}{b+c}+\frac{b}{a+c}+\frac{c}{a+b}< \frac{2a}{a+b+c}+\frac{2b}{a+b+c}+\frac{2c}{a+b+c}=2\)

\(\frac{a}{b+c}+\frac{b}{a+c}+\frac{c}{a+b}< 2\left(đpcm\right)\)

Trả lời :

\(\left[\frac{2}{3}\right]=0\)

\(\left[\frac{53}{4}\right]=\left[13\frac{1}{4}\right]=13\)

\(\left[-2021,01\right]=-2022\)

\(\left[\frac{-39}{5}\right]=\left[-7\frac{4}{5}\right]=-8\)

| x-2/3| = 1/3+2/5

             = 11/15

=> x-2/3=11/15          hoặc x-2/3=-11/15

            x= 7/5                      x       = -1/15

k cho mk nha

\(\left|x-\frac{2}{3}\right|-\frac{2}{5}=\frac{1}{3}\)

\(\Rightarrow\left|x-\frac{2}{3}\right|=\frac{1}{3}+\frac{2}{5}=\frac{11}{15}\)

\(\Rightarrow\orbr{\begin{cases}\Rightarrow x-\frac{2}{3}=\frac{11}{15}\\x-\frac{2}{3}=\frac{-11}{15}\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}\Rightarrow x=\frac{7}{15}\\x=\frac{-1}{15}\end{cases}}\)

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