bằng \(\frac{4}{35}\), k r giải cho

\(\begin{array}{l}B = \left( {\frac{{ - 3}}{{13}}} \right) + \frac{{16}}{{23}} + \left( {\frac{{ - 10}}{{13}}} \right) + \frac{5}{{11}} + \frac{7}{{23}}\\ = \left[ {\left( {\frac{{ - 3}}{{13}}} \right) + \left( {\frac{{ - 10}}{{13}}} \right)} \right] + \left[ {\frac{{16}}{{23}} + \frac{7}{{23}}} \right] + \frac{5}{{11}}\\ =  - 1 + 1 + \frac{5}{{11}}\\ = \frac{5}{{11}}\end{array}\)

`B= ( (-3)/13 + (-10)/13) + (16/23 + 7/23 ) +5/11`

`B= -13/13 + 23/23 +5/11`

`B=-1+1+5/11`

`B=0+5/11`

`B=5/11`

\(B=\left(-\dfrac{3}{13}\right)+\dfrac{16}{23}+\left(-\dfrac{10}{13}\right)+\dfrac{5}{11}+\dfrac{7}{23}\)

\(B=\left[\left(-\dfrac{3}{13}\right)+\left(-\dfrac{10}{13}\right)\right]+\left(\dfrac{16}{23}+\dfrac{7}{23}\right)+\dfrac{5}{11}\)

\(B=\left(-1\right)+1+\dfrac{5}{11}\)

\(B=\dfrac{5}{11}\)

P = \(\frac{2.3.4\left(1-9-11-13\right)}{5.6.7\left(1-9-11-13\right)}=\frac{2.3.4}{5.6.7}=\frac{4}{35}\)

\(\begin{array}{l}\left( {\frac{{20}}{7}.\frac{{ - 4}}{{ - 5}}} \right) + \left( {\frac{{20}}{7}.\frac{3}{{ - 5}}} \right) = \frac{{20}}{7}.\left( {\frac{{ - 4}}{{ - 5}} + \frac{3}{{ - 5}}} \right)\\ = \frac{{20}}{7}.\left( {\frac{{ - 1}}{{ - 5}}} \right) = \frac{{20}}{7}.\frac{1}{5} = \frac{{20}}{{35}} = \frac{4}{7}\end{array}\)

Ta có P=\(\frac{2.3.4\left(1-9-11-13\right)}{5.6.7\left(1-9-11-13\right)}\)=\(\frac{2.3.4}{5.6.7}\)=\(\frac{4}{35}\)

Chúc bạn hok tốt !

\(\frac{1999\times2011-1999}{2010\times1998-2010}\)=\(\frac{1999\times2010}{2010\times1997}\)=\(\frac{1999}{1997}\)

/HT\

co bao nhieu cachviet so 23 thanh tong cua3so le khac nhau

 \(\begin{array}{l}\left( {\frac{3}{5} + \frac{{ - 2}}{7}} \right) + \frac{{ - 1}}{5} = \left( {\frac{3}{5} + \frac{{ - 1}}{5}} \right) + \frac{{ - 2}}{7}\\ = \frac{2}{5} + \frac{{ - 2}}{7} = \frac{{14}}{{35}} + \frac{{ - 10}}{{35}} = \frac{4}{{35}}\end{array}\).