=(-2)+(-2)+...+(-2)

=-2x11

=-22

Lời giải:

$=(\frac{3}{5}+\frac{2}{5})+(\frac{5}{11}+\frac{16}{11})+(\frac{7}{13}+\frac{19}{13})$

$=\frac{5}{5}+\frac{22}{11}=\frac{26}{13}=1+2+2=5$

\(\frac{3}{5}+\frac{5}{1}+\frac{7}{13}\)\(+\frac{2}{5}+\frac{16}{11}+\frac{19}{13}\)

= \(\left(\frac{3}{5}+\frac{2}{5}\right)\)+\(\left(\frac{7}{13}+\frac{19}{13}\right)\)+5 +\(\frac{16}{11}\)

=1+2+5+\(\frac{16}{11}\)

=...

3/5 + 5/1 + 7/13 + 2/5 +16 /11+19/13

= (3/5+2/5)+(5/1+16/11)+(7/13+19/13)

=1+21/11+28/13

bạn tự tính tiếp nhé tiếp theo dễ lắm

\(\dfrac{3}{5}+\dfrac{6}{11}+\dfrac{7}{13}+\dfrac{2}{5}+\dfrac{16}{11}+\dfrac{19}{13}\\ =\left(\dfrac{3}{5}+\dfrac{2}{5}\right)+\left(\dfrac{6}{11}+\dfrac{16}{11}\right)+\left(\dfrac{7}{13}+\dfrac{19}{13}\right)\\ =\dfrac{5}{5}+\dfrac{22}{11}+\dfrac{26}{13}\\ =1+2+2\\ =5\)

5

`6/11+2/5+16/11+19/13+3/5+7/13`

`=(6/11+16/11)+(2/5+3/5)+(19/13+7/13)`

`=22/11+5/5+26/13`

`=2+1+2=5`

\(=\left(\dfrac{6}{11}+\dfrac{16}{11}\right)+\left(\dfrac{2}{5}+\dfrac{3}{5}\right)+\left(\dfrac{19}{13}+\dfrac{7}{13}\right)\)

\(=2+1+2\)

\(=5\)

\(\frac{3}{5}+\frac{6}{11}+\frac{7}{13}+\frac{2}{5}+\frac{16}{11}+\frac{19}{13}=\left(\frac{3}{5}+\frac{2}{5}\right)\left(\frac{6}{11}+\frac{16}{11}\right)\left(\frac{7}{13}+\frac{19}{13}\right)=1+2+2=5\)

Ta có:3/5+2/5=5/5=1; 6/11+16/11=22/11=2; 7/13+19/13=26/13=2

kết quả là 1+2+2=5

\(\frac{3}{5}+\frac{6}{11}+\frac{7}{13}+\frac{2}{5}+\frac{16}{11}+\frac{19}{13}\)

\(=\left(\frac{3}{5}+\frac{2}{5}\right)+\left(\frac{6}{11}+\frac{16}{11}\right)+\left(\frac{7}{13}+\frac{19}{13}\right)\)

\(=\frac{5}{5}+\frac{22}{11}+\frac{26}{13}\)

\(=1+2+2=5\)

3/5 + 5/1 + 7/13 + 2/5 + 16/11 + 19/13

= (3/5 + 2/5) + (5/1 + 16/11) + (7/13 + 19/13)

=    1 + 71/11 + 2

=       104/11

\(\left(\frac{3}{5}+\frac{2}{5}\right)+\left(\frac{6}{11}+\frac{16}{11}\right)+\left(\frac{7}{13}+\frac{19}{13}\right)\)

=         1             +                  2                +               2

= 5

\(=\frac{1}{1\cdot2}+\frac{1}{2\cdot3}+\frac{1}{3\cdot4}+\frac{1}{4\cdot5}+\frac{1}{5\cdot6}+\frac{1}{6\cdot7}\)

=     \(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}+\frac{1}{6}-\frac{1}{7}\)

=\(1-\frac{1}{7}\)

=\(\frac{6}{7}\)