Bài 2:
a)$\frac{-5}{9}$+ $\frac{4}{11}$+ $\frac{-4}{9}$
=($\frac{-5}{9}$+$\frac{-4}{9}$) +$\frac{4}{11}$
=(-1) +$\frac{4}{11}$
=$\frac{-7}{11}$
b) $\frac{-1}{5}$+ $\frac{7}{8}$+ $\frac{-4}{5}$+ $\frac{2}{16}$
= ($\frac{-1}{5}$+$\frac{-4}{5}$)+ ( $\frac{7}{8}$+ $\frac{2}{16}$ )
=(-1)+1
=0
OKI nha bạn Hihi
