\(\left(-\dfrac{1}{2}\right)-\left(-\dfrac{3}{5}\right)+\left(-\dfrac{1}{9}\right)+\dfrac{1}{127}-\dfrac{7}{18}+\dfrac{4}{35}-\left(-\dfrac{2}{7}\right)\)

\(=\left[-\dfrac{1}{2}-\dfrac{1}{9}-\dfrac{7}{18}\right]+\left[\dfrac{3}{5}+\dfrac{4}{35}+\dfrac{2}{7}\right]+\dfrac{1}{127}\)

\(=-\dfrac{18}{18}+\dfrac{35}{35}+\dfrac{1}{127}\)

\(=-1+1+\dfrac{1}{127}\)

\(=\dfrac{1}{127}\)

\(\left(-\frac{1}{2}\right)-\left(-\frac{3}{5}\right)+\left(-\frac{1}{9}\right)+\frac{1}{127}-\frac{7}{18}+\frac{4}{35}-\left(-\frac{2}{7}\right)=-\frac{1}{2}+\frac{3}{5}-\frac{1}{9}+\frac{1}{127}-\frac{7}{18}+\frac{4}{35}+\frac{2}{7}=\frac{1}{127}\)

a ) 11/125

b ) 1

\(=-\dfrac{1}{127}\)

\(A=\left\{\left[\left(\frac{-1}{2}+\frac{-1}{9}\right)-\frac{7}{18}\right]+\left(\frac{3}{5}+\frac{4}{35}+\frac{2}{7}\right)+\frac{1}{127}\right\}\)

\(\Rightarrow A=\left\{\left[\frac{-11}{18}-\frac{7}{18}\right]+1+\frac{1}{127}\right\}\)

\(A=\left(-1\right)+1+\frac{1}{127}\)

\(A=0+\frac{1}{127}\)

\(A=\frac{1}{127}\)

Ta có: \(\frac{-1}{2}+\frac{3}{5}+\frac{-1}{9}+\frac{1}{127}+\frac{-7}{18}+\frac{4}{35}+\frac{2}{7}\)

\(=\left(\frac{3}{5}+\frac{2}{7}+\frac{4}{35}\right)+\left(\frac{-1}{2}+\frac{-1}{9}+\frac{-7}{18}\right)+\frac{1}{127}\)

\(=\left(\frac{21}{35}+\frac{10}{35}+\frac{4}{35}\right)+\left(\frac{-9}{18}+\frac{-2}{18}+\frac{-7}{18}\right)+\frac{1}{127}\)

\(=\frac{35}{35}+\frac{-18}{18}+\frac{1}{127}\)

\(=1+\left(-1\right)+\frac{1}{127}\)

\(=\frac{1}{127}\)

A 50

b 97

c 74

k cho mình nhé

7/5 x 5/8 x30/7x16x1/1000 = 3/50

1/2 + 3/5 +1/9 +1/217+7/18+4/35-2/7= 311/21

các bạn nhớ diễn giải ra nhá