3/4 + 2/3 - 1/6 = 27/12 - 1/6 = 7/6

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

\(=\frac{3}{4}+\frac{2}{3}\)

\(=\frac{17}{12}\)

\(=\frac{17}{12}-\frac{1}{6}\)

\(=\frac{90}{72}\)

17/12-1/6=5/4

Ta có : \(\frac{\frac{3}{5}+\frac{3}{7}-\frac{1}{3}+\frac{3}{11}}{\frac{6}{5}+\frac{6}{7}-\frac{2}{3}+\frac{6}{11}}=\frac{\frac{3}{5}+\frac{3}{7}-\frac{1}{3}+\frac{3}{11}}{2\left(\frac{3}{5}+\frac{3}{7}-\frac{1}{3}+\frac{3}{11}\right)}=\frac{1}{2}\)

Lại có : \(\frac{\left(\frac{1}{4}-\frac{1}{5}-\frac{1}{20}\right).2021}{\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{99.100}}=\frac{0.2021}{\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{99.100}}=0\)

Khi đó \(B=\frac{1}{2}+0=\frac{1}{2}\)

Ta có : 

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

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

\(=\)\(\frac{2}{7}-\frac{1}{\frac{7}{2}}\)

\(=\)\(\frac{2}{7}-\frac{2}{7}\)

\(=\)\(0\)

Chúc bạn học tốt ~ 

thank nha

k cho mk nhé .OK

mik học lớp 5 mik bít đấy

\(\frac{17}{2}-\left|2x-\frac{5}{2}\right|=-\frac{7}{6}\)

\(\left|2x-\frac{5}{2}\right|=\frac{17}{2}-\frac{-7}{6}\)

\(\left|2x-\frac{5}{2}\right|=\frac{51}{6}+\frac{7}{6}\)

\(\left|2x-\frac{5}{2}\right|=\frac{29}{3}\)

\(2x-\frac{5}{2}=\frac{29}{3}\)hoặc \(2x-\frac{5}{2}=\frac{-29}{3}\)

Trường hợp 1:

\(2x-\frac{5}{2}=\frac{29}{3}\)

\(2x=\frac{29}{3}+\frac{5}{2}\)

\(2x=\frac{73}{6}\)

\(x=\frac{73}{6}:2\)

\(x=\frac{73}{12}\)

Trường hợp 2:

\(2x-\frac{5}{2}=\frac{-29}{3}\)

\(2x=\frac{-29}{3}+\frac{5}{2}\)

\(2x=\frac{-43}{6}\)

\(x=\frac{-43}{6}:2\)

\(x=\frac{-43}{12}\)

Vậy \(x=\frac{73}{12}\)hoặc \(x=\frac{-43}{12}\)

17/2 - |2x-5/2| = -7/6

         |2x-5/2|= 17/2 - (-7/6)

         |2x-5/2|= 29/3

2x-5/2= 29/3      hoặc     2x-5/2= -29/3

Tự tính 2 kết quả

17/2-|2x-5/2|=-7/6

=>-|2x-5/2|=-7/6-17/2    (chuyển vế đổi dấu)

=>-|2x-5/2|=-29/3          (thực hiện pép tính vế phải)

=>.|2x-5/2|=29/3             (bỏ dấu trừ cả hai vế)

như ta đã biết với a bất kì ta luôn có |a|=-a khi a<0     |a|=a khi a>0 hoặc a=0

xét trường hợp 2x-5/2>=0 =>x>=1.25

ta có |2x-5/2|=2x-5/2      (vì lớn hơn hoặc bằng 0 nên nó bằng chính nó)

khi đó 2x-5/2=29/3=>2x=73/6=>x=73/12     (giải phương trình)

tương tự 2x-5/2<0=>x<1.25

ta có |2x-5/2|=-(2x-5/2)=5/2-2x

khi đó 5/2-2x=29/3=>2x=5/2-29/3=-43/6=>x=-43/12   (như trên)

vậy x=73/12 và x=-43/12

10/12-1/2-1/3

=10/12-6/12-4/12

=4/12-4/12

=0

10/12-1/2-1/3=1/3-1/3

                   =0

\(\frac{10}{12}-\frac{1}{2}-\frac{1}{3}\)

\(=\frac{10}{12}-\frac{6}{12}-\frac{4}{12}\)

\(=\frac{10-6-4}{12}\)

\(=0\)

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

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, c1 | ( 6/11 + 5/11 ) x 3/7 = 1 x 3/7 = 3/7

    c2 | ( 6/11 + 5/11 ) x 3/7 = 3/7 x 6/11 + 3/7 x 5/11 = 18/77 + 15/77 = 33/77 = 3/7

B, c1 | 3/5 x 7/9 + 3/5 x 2/9 = 3/5 x ( 7/9 + 2/9 ) = 3/5 x 1 = 3/5

    c2 | 3/5 x 7/9 + 3/5 x 2/9 = 7/15 + 2/15 = 9/15 = 3/5

k cho minh nhe

chuc ban hoc tot

\(A=\frac{-11}{13}\)

\(B=\frac{-1}{64}\)
 

A=\(\frac{1}{3}-\frac{3}{5}+\frac{5}{7}-\frac{7}{9}+\frac{9}{11}-\frac{11}{13}-\frac{9}{11}+\frac{7}{9}-\frac{5}{7}+\frac{3}{5}-\frac{1}{3}\)

A=[ \(\frac{1}{3}-\frac{1}{3}\)] + [ \(-\frac{3}{5}+\frac{3}{5}\)] + [  \(-\frac{5}{7}+\frac{5}{7}\)] + [  \(-\frac{7}{9}+\frac{7}{9}\)] + [  \(-\frac{9}{11}+\frac{9}{11}\)] \(-\frac{11}{13}\)

Các bạn tự làm tiếp nhé!Sorry

4/5 - 2/3 + 1/7 

= 2/15 + 1/7 

= 29/105  

4/5-2/3+1/7=2/15+1/7=29/105

mình không biết làm