a Đ

b S

c S

d Đ

a ) S 

b ) Đ

c ) S

d ) Đ

k cho mk nhé 

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

\(a,\left(\frac{6}{11}+\frac{5}{11}\right)\times\frac{3}{7}\)

Cách 1: \(\left(\frac{6}{11}+\frac{5}{11}\right)\times\frac{3}{7}=1\times\frac{3}{7}=\frac{10}{7}\)

Cách 2: \(\left(\frac{6}{11}+\frac{5}{11}\right)\times\frac{3}{7}=\frac{6}{11}\times\frac{3}{7}+\frac{5}{11}\times\frac{3}{7}=\frac{18}{77}+\frac{15}{77}=\frac{33}{77}=\frac{3}{7}\)

\(b,\frac{3}{5}\times\frac{7}{9}+\frac{3}{5}\times\frac{2}{9}\)

Cách 1: \(\frac{3}{5}\times\frac{7}{9}+\frac{3}{5}\times\frac{2}{9}=\frac{7}{15}+\frac{2}{15}=\frac{9}{15}\)

Cách 2: \(\frac{3}{5}\times\frac{7}{9}+\frac{3}{5}\times\frac{2}{9}=\frac{3}{5}\times1=\frac{3}{5}\)

P/s: Ý B có vấn đề thì phải

\(a,\left(\frac{6}{11}+\frac{5}{11}\right)x\frac{3}{7}\)

\(=\frac{11}{11}=1x\frac{3}{7}\)

\(=\frac{3}{7}\)

cach 2 

\(\frac{6}{11}x\frac{3}{7}+\frac{5}{11}x\frac{3}{7}\)

\(=\frac{18}{77}+\frac{15}{77}\)

\(=\frac{33}{77}=\frac{3}{7}\)

\(b,\frac{3}{5}x\frac{7}{9}+\frac{3}{5}x\frac{2}{9}\)

\(=\frac{21}{45}+\frac{6}{45}\)

\(=\frac{27}{45}=\frac{3}{5}\)

cách 2 : 

\(\frac{3}{5}x\left(\frac{7}{9}+\frac{2}{9}\right)\)

\(=\frac{3}{5}x\frac{9}{9}\)

\(=\frac{27}{45}=\frac{3}{5}\)

a)\(\dfrac{5}{7}+\dfrac{4}{9}=\dfrac{45}{63}+\dfrac{28}{63}=\dfrac{73}{63}\) ; \(\dfrac{9}{11}+\dfrac{3}{8}=\dfrac{72}{88}+\dfrac{33}{88}=\dfrac{105}{88}\)

\(\dfrac{4}{5}-\dfrac{2}{3}=\dfrac{12}{15}-\dfrac{10}{15}=\dfrac{2}{15}\); \(\dfrac{16}{25}-\dfrac{2}{5}=\dfrac{16}{25}-\dfrac{10}{25}=\dfrac{6}{25}\)

b)\(5+\dfrac{3}{5}=\dfrac{25}{5}+\dfrac{3}{5}=\dfrac{28}{5};10-\dfrac{9}{16}=\dfrac{160}{16}-\dfrac{9}{16}=\dfrac{151}{16}\)

\(\dfrac{2}{3}-\left(\dfrac{1}{6}+\dfrac{1}{8}\right)=\dfrac{2}{3}-\left(\dfrac{8}{48}+\dfrac{6}{48}\right)=\dfrac{2}{3}-\dfrac{14}{48}=\dfrac{32}{48}-\dfrac{14}{48}=\dfrac{3}{8}\)

\(\frac{1}{11}+\frac{2}{11}+\frac{3}{11}+\frac{4}{11}+\frac{5}{11}+\frac{6}{11}+\frac{7}{11}+\frac{8}{11}+\frac{9}{11}+\frac{10}{11}\)

\(=\frac{1+2+3+4+5+6+7+8+9+10}{11}\)

\(=\frac{\left(1+10\right)+\left(2+9\right)+\left(3+8\right)+\left(4+7\right)+\left(5+6\right)}{11}\)

\(=\frac{11+11+11+11+11}{11}\)

\(=\frac{11\cdot5}{11}=5\)

\(= \frac{1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10}{11}\)

\(1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10 = 55\)

Vậy là bằng 55/11 nhé bạn

\(\frac{9}{8}>\frac{8}{9}\)

\(\frac{16}{23}>\frac{16}{25}\)

\(\frac{8}{11}< \frac{8}{10}\)

\(\frac{10}{13}>\frac{19}{26}\)

\(\frac{13}{15}< \frac{11}{10}\)

\(\frac{11}{9}=\frac{44}{36}\)

9/8 > 8/9 

16/23 > 16/25 

8/11 < 8/10 

10/13 > 19/26 

13/15 < 11/10 

11/9 = 44/36 

Tham khảo nha !

Chúc bạn học giỏi !

4 x 4 = 16

4 x 1 = 4

4 x 5 = 20

4 x 8 = 32

4 x 9 = 36

9 x 9 = 81 

4 x 4 = 16

4 x 1 = 4

4 x 5 = 20

4 x 8 = 32

4 x 9 = 36

9 x 9 = 81

Chúc bạn học tốt !!!

\(\frac{3}{4}\times\frac{9}{7}\times\frac{11}{25}\)

\(=\frac{297}{700}\)

Chúc bn học tốt!!!!!

\(\frac{3}{4}x\frac{9}{7}x\frac{11}{25}\)

= \(\frac{3}{4}x\frac{11}{25}x\frac{9}{7}\)

=\(\frac{33}{100}x\frac{9}{7}\)

=\(\frac{297}{700}\)

a,\(\frac{6\times7\times8}{8\times9\times10}=\frac{6\times7}{9\times10}=\frac{7}{15}\)

\(\frac{7}{8}.\frac{9}{11}.\frac{8}{3}:\frac{2}{9}\)

\(=\frac{7.9.8.9}{8.11.3.2}\)

\(=\frac{189}{11}\)

Dấu \(\left(.\right)\)là dấu nhân nhé