`1/2:3/4+5/6:3/4-2/8:3/4`

`=1/2 xx 4/3 + 5/6 xx 4/3 - 2/8 xx 4/3`

`=4/3 xx ( 1/2 + 5/6 - 2/8)`

`=4/3 xx ( 1/2 + 5/6 - 1/4 )`

`=4/3 xx ( 6/12 + 10/12 - 3/12)`

`=4/3 xx ( 16/12 - 3/12)`

`=4/3 xx 13/12`

`=13/9`

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

\(\dfrac{1}{2}+\dfrac{1}{3}+\dfrac{1}{4}+\dfrac{1}{5}+\dfrac{4}{5}+\dfrac{3}{4}+\dfrac{2}{3}+\dfrac{1}{2}\)

\(=\left(\dfrac{1}{2}+\dfrac{1}{2}\right)+\left(\dfrac{1}{3}+\dfrac{2}{3}\right)+\left(\dfrac{1}{4}+\dfrac{3}{4}\right)+\left(\dfrac{1}{5}+\dfrac{4}{5}\right)\)

=1+1+1+1

=4

=(12+12)+(13+23)+(14+34)+(15+45)=(12+12)+(13+23)+(14+34)+(15+45)
=(12+12)+(13+23)+(14+34)+(15+45)

=1+1+1+1

=4

= 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

A = \(\dfrac{1}{2}\)+ \(\dfrac{1}{3}\)+ \(\dfrac{1}{4}\)+ \(\dfrac{1}{2}\)+ \(\dfrac{2}{3}\)+ \(\dfrac{3}{4}\)

A = ( \(\dfrac{1}{2}\)+ \(\dfrac{1}{2}\)) + ( \(\dfrac{1}{4}\)+\(\dfrac{3}{4}\)) +( \(\dfrac{1}{3}\)+ \(\dfrac{2}{3}\))

A = 1 + 1 + 1

A = 3

B = ( \(\dfrac{3}{4}\) + \(\dfrac{5}{7}\)+ \(\dfrac{16}{64}\)+ \(\dfrac{2}{7}\)) - 2

B = ( \(\dfrac{3}{4}\)+ \(\dfrac{1}{4}\)) + ( \(\dfrac{5}{7}\)+ \(\dfrac{2}{7}\)) - 2

B = 1 + 1 - 2

B = 2 - 2

B = 0

tao là Lan xinh gái

vãi đề thua luôn

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

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

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

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

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

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

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

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

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

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

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

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

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

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