giúp mình với

bạn đổi ra số thập phân rồi làm đi

\(\dfrac{3}{4}\times\dfrac{4}{5}+\dfrac{5}{6}\times\dfrac{6}{7}\times\dfrac{7}{8}\)
\(=\dfrac{3}{5}+\dfrac{5}{8}\)
\(=\dfrac{24}{40}+\dfrac{25}{40}\)
\(=\dfrac{49}{40}\)
#Đang Bận Thở

\(\dfrac{3}{4}\times\dfrac{4}{5}\times\dfrac{5}{6}\times\dfrac{6}{7}\div\dfrac{1}{7}\)

\(=\dfrac{3}{4}\times\dfrac{4}{5}\times\dfrac{5}{6}\times\dfrac{6}{7}\times\dfrac{7}{1}\)

\(=\dfrac{3\times4\times5\times6\times7}{4\times5\times6\times7\times1}\)

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

\(\dfrac{1}{1\times2}+\dfrac{1}{2\times3}+\dfrac{1}{3\times4}+\dfrac{1}{4\times5}+\dfrac{1}{5\times6}+\dfrac{1}{6\times7}+\dfrac{1}{7\times8}\)

\(=1-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{5}+\dfrac{1}{6}-\dfrac{1}{7}+\dfrac{1}{7}-\dfrac{1}{8}\)

\(=1-\dfrac{1}{8}=\dfrac{7}{8}\)

$8\times 427\times 3+6\times 563\times 4$

$=24\times 427+24\times 563$

$=24\times (427+563)$

$=24\times 1000$

$=24000$

$8\times 427\times 3+6\times 563\times 4$

$=24\times 427+24\times 563$

$=24\times (427+563)$

$=24\times 1000$

$=24000$

8 x 427 x 3 + 6 x 573 x 4

= (8 x 3) x 427 + 573 x (6 x 4)

= 24 x 427 + 573 x 24

= 24 x (427+573)

= 24 x 1000

= 24 000

2/3×3/4×4/5÷1/5=2

2/5×3/4×5/6÷3/4=0.33333333333......

2/3 x 3/4 x 4/5 : 1/5 = 6/12 x 4/5 :1/5 = 24/60 :1/5 = 4/10 : 1/5 = 4/10 x 5/1 = 20/10 = 2

2/5 x 3/4 x 5/6 : 3/4 = 6/20 x 5/6 : 3/4 = 3/10 x 5/6  : 3/4 = 15/60 : 3/4 = 1/4 : 3/4 = 1/4 x 4/3 = 4/12 = 1/3

k cho mk nha!

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

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

\(=\frac{2\times3\times4\times5}{3\times4\times5\times1}\)

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

\(=2\)

=3-2/2*3+4-3/3*4+5-4/4*5+6-5/5*6    =3/2*3-2/2*3+4/3*4-3/3*4+5/4*5-4/4*5+6/5*6-5/5*6       =1/2-1/6   =4/12=1/3

Mình không hiểu 

= 51/20

----------------------------------

= 3/14

------------------------------------

= 4/7 - 2/7 

= 2/7

--------------------------------------

= 17/45

---------------------------------------

= 2/3 

--------------------------------------

= 2 x 1/4 

= 1/2

1/9

\(\dfrac{1}{2}\times\dfrac{2}{3}\times\dfrac{3}{4}\times\dfrac{4}{5}\times\dfrac{5}{6}\times\dfrac{6}{7}\times\dfrac{7}{8}\times\dfrac{8}{9}\)

\(=\dfrac{1\times2\times3\times4\times5\times6\times7\times8}{2\times3\times4\times5\times6\times7\times8\times9}\)

\(=\dfrac{1}{9}\)

1/9

= 1/10

dễ sao bạn ko tự làm đi