cần gấp ạ
\(a)\dfrac{-5}{11}+\left(\dfrac{-6}{11}+1\right)\\ =\dfrac{-5}{11}+\left(\dfrac{-6}{11}+\dfrac{11}{11}\right) \\ =\dfrac{-5}{11}+\dfrac{5}{11}\\ =\dfrac{0}{11}=0 \\ b)\dfrac{2}{3}+\left(\dfrac{5}{7}+\dfrac{-2}{3}\right)\\ =\dfrac{2}{3}+\left(\dfrac{15}{21}+\dfrac{-14}{21}\right)\\ =\dfrac{2}{3}+\dfrac{1}{21}\\ =\dfrac{14}{21}+\dfrac{1}{21}\\ =\dfrac{15}{21}=\dfrac{5}{7}\\ c)\left(\dfrac{-1}{4}+\dfrac{5}{8}\right)+\dfrac{-3}{8}\\ =\left(\dfrac{-2}{8}+\dfrac{5}{8}\right)+\dfrac{-3}{8}\\ =\dfrac{3}{8}+\dfrac{-3}{8}\\ =\dfrac{0}{8}=0\)
\(a)\)\(\dfrac{-5}{11}+\left(\dfrac{-6}{11}+1\right)\)
\(=\left(\dfrac{-5}{11}+\dfrac{-6}{11}\right)+1\)
\(=-1+1\)
\(=0\)
\(b)\)\(\dfrac{2}{3}+\left(\dfrac{5}{7}+\dfrac{-2}{3}\right)\)
\(=\left(\dfrac{2}{3}+\dfrac{-2}{3}\right)+\dfrac{5}{7}\)
\(=0+\dfrac{5}{7}\)
\(=\dfrac{5}{7}\)
\(c)\)\(\left(\dfrac{-1}{4}+\dfrac{5}{8}\right)+-\dfrac{3}{8}\)
\(=\dfrac{-1}{4}+\left(\dfrac{5}{8}+\dfrac{-3}{8}\right)\)
\(=\dfrac{-1}{4}+\dfrac{2}{8}\)
\(=\dfrac{-1}{4}+\dfrac{1}{4}\)
\(=0\)
#Ayumu
giúp em với ạ em cần gấp ạ
giúp em với ạ em cần gấp ạ
GIẢI GẤP GIÚP T Ạ, T CẦN GẤP 
