\(\dfrac{2}{1}+\dfrac{12}{56}=\dfrac{112+12}{56}=\dfrac{122}{56}=\dfrac{61}{28}\)

\(\left(\dfrac{8+7}{15}\right):\dfrac{2}{11}\)

\(1:\)\(\dfrac{2}{11}\)

\(\dfrac{11}{2}\)

\(\dfrac{2}{1}+\dfrac{12}{56}=\dfrac{112}{56}+\dfrac{12}{56}=\dfrac{122}{56}=\dfrac{61}{28}\)

\(=\left(\dfrac{8}{15}+\dfrac{7}{15}\right)\times\dfrac{11}{2}=\dfrac{15}{15}\times\dfrac{11}{2}=1\times\dfrac{11}{2}=\dfrac{11}{2}\)

a ,b

cách 1 : cộng 2 số trong ngặc rồi tính bình thường 

cách 2 : nhân phân phối ra rồi tính nhân chia trước cộng trừ sau

c,d

cách 1 : tính bình thường, nhân chia trc cộng trừ sau

cách 2 : đặt nhân tử ( thừa số ) chung

Cách 1 : \((\frac{6}{11}+\frac{5}{11})\cdot\frac{3}{7}=1\cdot\frac{3}{7}=\frac{3}{7}\)

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

Cách 1 dễ rồi nha

Cách 2 : \(\frac{6}{7}:\frac{2}{5}-\frac{4}{7}:\frac{2}{5}=\frac{15}{7}-\frac{10}{7}=\frac{5}{7}\)

Cách 1 tự làm

Cách 2 : \(\frac{3}{5}\cdot(\frac{7}{9}-\frac{2}{9})=\frac{3}{5}\cdot\frac{5}{9}=\frac{1}{3}\)

Cách 1 : ...

Cách 2 : \((\frac{8}{15}+\frac{7}{15}):\frac{2}{11}=1:\frac{2}{11}=\frac{2}{11\cdot1}=\frac{2}{11}\)

a) Cách 1:

(6/7 - 4/7):2/5

=2/7 : 2/5

=5/7

Cách 2:

(6/7 - 4/7):2/5

=6/7:2/5 - 4/7:2/5

=15/7-10/7

=5/7

b) Cách 1:

8/15:2/11+7/15:2/11

=44/15+77/30

=165/30=11/2

Cách 2:

8/15:2/11+7/15:2/11

= (8/15+7/15):2/11

=1:2/11

=11/2

A.3/7

B.3/5

C.5/7

D.11/2

k hộ mình nha!

=(8/15+7/15):2/11

=1:2/11

=11/2

\(\frac{8}{15}:\frac{2}{11}+\frac{7}{15}:\frac{2}{11}\)

\(=\frac{8}{15}\times\frac{11}{2}+\frac{7}{15}\times\frac{11}{2}\)

\(=\frac{11}{2}\times\left(\frac{8}{15}+\frac{7}{15}\right)\)

\(=\frac{11}{2}\times1\)

\(=\frac{11}{2}\)

P/s tham khảo nha

cách 1 :

\(\frac{3}{5}\chi\frac{7}{9}+\frac{3}{5}\chi\frac{2}{9}\)

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

= \(\frac{3}{5}\chi1\)

=  \(\frac{3}{5}\)

cách 2 : 

\(\frac{3}{5}\chi\frac{7}{9}+\frac{3}{5}\chi\frac{2}{9}\)

= \(\frac{7}{15}\)   +  \(\frac{2}{15}\)

=        \(\frac{9}{15}=\frac{3}{5}\)

\(C1:\frac{3}{5}.\frac{7}{9}+\frac{3}{5}.\frac{2}{9}\)                                            \(C2:\frac{3}{5}.\frac{7}{9}+\frac{3}{5}.\frac{2}{9}\)

\(=\frac{3}{5}\left(\frac{7}{9}+\frac{2}{9}\right)=\frac{3}{5}.1=\frac{3}{5}\)                     \(=\frac{7}{15}+\frac{2}{15}=\frac{3}{5}\)

\(C1:\frac{8}{15}:\frac{2}{11}+\frac{7}{15}:\frac{2}{11}\)                                      \(C2:\frac{8}{15}:\frac{2}{11}+\frac{7}{15}:\frac{2}{11}\)

\(=\left(\frac{8}{15}+\frac{7}{15}\right):\frac{2}{11}=1:\frac{2}{11}=\frac{11}{2}\)           \(=\frac{44}{15}+\frac{77}{30}=\frac{88}{30}+\frac{77}{30}=\frac{11}{2}\)

Giải chi tiết cho mình nha

2/5 + 11/15 = 17/15
7/8 - 7/9 = 7/72
11/13 x 26/31 = 22/31
16/24 : 4 = 1/6
30 : 6/5 = 25
9/16 : 4 = 9/64
1/2 : 1/3 x 8/15 = 3/2 x 8/15 = 4/5

a, (6/11+5/11)x3/17

c1:=1x3/17

    =3/17

c2:=6/11x3/17+5/11x3/17

    =18/197+15/187

    =33/187

    =3/17

b,3/5x7/9-3/5x2/9

c1:=21/45-6/45

=15/45

=1/3

c2:=3/5x(7/9-2/9)

=3/5x5/9

=1/3

c,( 6/7-4/7):2/5

c1:=2/7:2/5

=2/7x5/2

=5/7

c2,6/7:2/5-4/7:2/5

=6/7x5/2-4/7x5/2

=15/7-10/7

=5/7

d,8/15:2/11+7/15:2/11

c1:=(8/15+7/15):2/11

=1x11/2

=11/2

c2:=8/15x11/2+7/15x11/2

=88/30+77/30

=165/30

=11/2

a) (\(\frac{6}{11}\) + \(\frac{5}{11}\)) x \(\frac{3}{17}\)=  \(\frac{11}{11}\) x \(\frac{3}{17}\)= \(1\) x\(\frac{3}{17}\)= \(\frac{3}{17}\)

b) \(\frac{3}{5}\)x\(\frac{7}{9}\)- \(\frac{3}{5}\)x \(\frac{2}{9}\) = \(\frac{3}{5}\)x (\(\frac{7}{9}\)- \(\frac{2}{9}\))= \(\frac{3}{5}\) x  \(\frac{5}{9}\)= \(\frac{3}{9}\)

c) (\(\frac{6}{7}\)- \(\frac{4}{7}\)) : \(\frac{2}{5}\)= \(\frac{2}{7}\) x \(\frac{5}{2}\)= \(\frac{5}{7}\)

d) \(\frac{8}{15}\) : \(\frac{2}{11}\) + \(\frac{7}{15}\): \(\frac{2}{11}\)=  ( \(\frac{8}{15}\)+ \(\frac{7}{15}\)) x \(\frac{11}{2}\)= 1 x \(\frac{11}{2}\)= \(\frac{11}{2}\)

Chúc học tốt nha!