= 3/2 + 2/3 + 2/4 + 2/5

= (6/4 + 2/4) + (2/3 + 2/5)

= 8/4 + 16/ 15 

= 46/15

=46/15

1/2 + 1/3 + 1/4 + 1/5 + 4/5 + 3/4 + 2/3 + 1/2

= (1/2 + 1/2) + (1/3 + 2/3) + (1/4 + 3/4) + (1/5 + 4/5)

= 1 + 1 + 1 + 1

= 4

`3/4 +1/2 +1/4 +3/2`

`= (3/4+1/4)+(1/2+3/2)`

`= 4/4 + 4/2`

`=1+2`

`=3`

3/4+1/2+1/4+3/2

=(3/4+1/4)+(1/2+3/2)

=1+2

=3

\(\frac{1}{1}-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}\)

\(=1-\frac{1}{4}=\frac{3}{4}\)

= 1/1 -(1/2-1/2) -(1/3-1/3)-1/4

=1-1/4=3/4

\(\left(1-\dfrac{1}{2}\right)\times\left(1-\dfrac{1}{3}\right)\times\left(1-\dfrac{1}{4}\right)\times\left(1-\dfrac{1}{6}\right)\times\left(1-\dfrac{1}{6}\right)\)

\(=\dfrac{1}{2}\times\dfrac{2}{3}\times\dfrac{3}{4}\times\dfrac{4}{5}\times\dfrac{5}{6}\)

\(=\dfrac{1\times2\times3\times4\times5}{2\times3\times4\times5\times6}\)

\(=\dfrac{1}{6}\)

=1/2*2/3*3/4*4/5*5/6

=1/6

\(\left(\frac{1}{2}-\frac{1}{3}+\frac{1}{4}-\frac{1}{5}\right):\left(\frac{1}{4}-\frac{1}{6}\right)\)

\(=\left(\frac{1}{2.3}+\frac{1}{4.5}\right):\frac{2}{4.6}\)

\(=\left(\frac{1}{6}+\frac{1}{20}\right).2.6\)

\(=\frac{13}{60}.2.6=\frac{13}{5}\)

13/6

 dễ mà anh

mấy bn giúp mik với

\(\frac{11}{2}\): \(\frac{11}{3}\): \(\frac{11}{4}\)

= \(\frac{11}{2}\): ( \(\frac{3}{11}\): \(\frac{4}{11}\)

\(\frac{1}{2}\times\frac{1}{3}+\frac{1}{3}\times\frac{1}{4}+\frac{1}{4}\times\frac{1}{5}+\frac{1}{5}\times\frac{1}{6}\)

\(=\frac{1}{2x3}+\frac{1}{3x4}+\frac{1}{4x5}+\frac{1}{5x6}\)

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

\(=\frac{1}{2}-\frac{1}{6}=\frac{2}{6}=\frac{1}{3}\)

\(\frac{1}{2}.\frac{1}{3}+\frac{1}{3}.\frac{1}{4}+\frac{1}{4}.\frac{1}{5}+\frac{1}{5}.\frac{1}{6}\)

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

\(=\frac{1}{2}-\frac{1}{6}\)

\(=\frac{1}{3}\)

(1-1/2).(1-1/3).(1-1/4).(1-1/5)

=1/2.2/3.3/4.4/5

=1/5

(1-1/2).(1-1/3).(1-1/4).(1-1/5)

1.(1/2-1/3-1/4-1/5)

1/5