1/5*2/7:1/7=1/5*2/7*7.

               =(1*2*7)/(5*7*1).

               =2/5.

tk mk nha các bn.

-chúc ai tk mk học giỏi nha-

\(\frac{1}{5}.\frac{2}{7}.7=\frac{2}{5}\)

9/2

k mình nha

= \(\frac{9}{2}\)

\(\frac{2}{5}\)x \(\frac{3}{8}\)+ \(\frac{3}{4}\)

= \(\frac{3}{20}\)+ \(\frac{3}{4}\)

= \(\frac{9}{10}\)

tk nhé năn nỉ đó

2/5*3/8+3/4=3/20+3/4=18/20=9/10

bằng \(\frac{23}{12}\)

đồng ý

=\(\frac{2001x2004x1001x2006}{2004x2006x2001x2002}\)=\(\frac{1}{2}\)

\(=\frac{2001.2004.1001.2002}{2004.2006.2001.2002}=\frac{1.1.1001.1}{1.2006.1.1}=\frac{1001}{2006}\)

a) 5/4 + 3/4= 8/4=2

b)5/6+1/6=6/6=1

ai tk mình tk lại cho nha!!!!

a)\(\frac{5}{4}+\frac{12}{16}=\frac{5}{4}+\frac{3}{4}=\frac{8}{4}=2\)

b)\(\frac{5}{6}+\frac{4}{24}=\frac{5}{6}+\frac{1}{6}=\frac{6}{6}=1\)

K mk nha 

bằng 2 nha

17/11 + 17/15 - 6/11 + 18/15 

= ( 17/11 + 6/11 )  - ( 7/15 + 8/15 ) 

= 21/11 - 15/15 

= 21/11 -1 

= 10/11

= 55 nha bn 

Mk là ARMY NÈ

=55 NHA BẠN

\(a.\left(\frac{6}{11}+\frac{5}{11}\right).\frac{3}{7}=1\cdot\frac{3}{7}=\frac{3}{7}b.\frac{3}{5}\cdot\frac{7}{9}+\frac{3}{5}\cdot\frac{2}{9}=\frac{3}{5}\cdot\left(\frac{7}{9}+\frac{2}{9}\right)=\frac{3}{5}\cdot1=\frac{3}{5}\)