Câu trả lời là \(\frac{5}{9}\)phải không ?

\(\frac{5}{9}\)

loi nhanh nha

\(a)\dfrac{5}{12}+\dfrac{5}{3}+\dfrac{2}{12}+\dfrac{2}{3}\)

\(=\left(\dfrac{5}{12}+\dfrac{2}{12}\right)+\left(\dfrac{5}{3}+\dfrac{2}{3}\right)\)

\(=\dfrac{7}{12}+\dfrac{7}{3}\)

\(=\dfrac{7}{12}+\dfrac{28}{12}\)

\(=\dfrac{35}{12}\)

\(b)\dfrac{5}{9}.\dfrac{7}{13}+\dfrac{5}{9}-\dfrac{5}{9}.\dfrac{3}{13}\)

\(=\dfrac{5}{9}.1.\dfrac{7}{13}+\dfrac{5}{9}-\dfrac{5}{9}.\dfrac{3}{13}\)

\(=\dfrac{5}{9}.\left(1+\dfrac{7}{13}-\dfrac{3}{13}\right)\)

\(=\dfrac{5}{9}.\dfrac{17}{13}\)

\(=\dfrac{85}{117}\)

Bài 1 :

a) \(\frac{12}{21}-\frac{3}{7}+\left(-\frac{2}{3}\right)=\frac{4}{7}-\frac{3}{7}+\left(-\frac{2}{3}\right)=\frac{1}{7}-\frac{2}{3}=-\frac{11}{21}\)

b) \(\left(-\frac{25}{13}\right)+\left(-\frac{9}{17}\right)+\frac{12}{13}+\left(-\frac{25}{17}\right)\)

\(=\left[\left(-\frac{25}{13}\right)+\frac{12}{13}\right]+\left[\left(-\frac{9}{17}\right)+\left(-\frac{25}{17}\right)\right]\)

\(=-1+\left(-2\right)=-1-2=-3\)

c) \(\frac{5}{9}\cdot\frac{7}{13}+\frac{5}{9}\cdot\frac{9}{13}-\frac{5}{9}\cdot\frac{3}{13}=\frac{5}{9}\left(\frac{7}{13}+\frac{9}{13}-\frac{3}{13}\right)=\frac{5}{9}\cdot1=\frac{5}{9}\)

Bài 2 :

a)  \(\frac{2}{3}x+\frac{5}{7}=\frac{3}{10}\)

=> \(\frac{2}{3}x=\frac{3}{10}-\frac{5}{7}=-\frac{29}{70}\)

=> \(x=\left(-\frac{29}{70}\right):\frac{2}{3}=\left(-\frac{29}{70}\right)\cdot\frac{3}{2}=-\frac{87}{140}\)

b) \(x:\frac{5}{2}-\frac{1}{2}=-\frac{2}{3}\)

=> \(x:\frac{5}{2}=-\frac{2}{3}+\frac{1}{2}=-\frac{1}{6}\)

=> \(x=\left(-\frac{1}{16}\right)\cdot\frac{5}{2}=-\frac{5}{32}\)

c) Bạn chỉ cần xét hai trường hợp âm và dương thôi :>

ta có \(\frac{\frac{4}{5}-\frac{4}{11}+\frac{4}{13}}{\frac{9}{5}-\frac{9}{11}+\frac{9}{13}}+\frac{\frac{5}{7}+\frac{5}{11}-\frac{5}{13}}{\frac{9}{7}+\frac{9}{11}-\frac{9}{13}}\)

       \(=\frac{4\left(\frac{1}{5}-\frac{1}{11}+\frac{1}{13}\right)}{9\left(\frac{1}{5}-\frac{1}{11}+\frac{1}{13}\right)}+\frac{5\left(\frac{1}{7}+\frac{1}{11}-\frac{1}{13}\right)}{9\left(\frac{1}{7}+\frac{1}{11}-\frac{1}{13}\right)}\)

           \(=\frac{4}{9}+\frac{5}{9}=\frac{9}{9}=1\)

\(-\dfrac{29}{39}\)

\(\dfrac{5}{9}\times\dfrac{-7}{13}+\dfrac{5}{9}\times\dfrac{-9}{13}+\dfrac{5}{9}-\dfrac{3}{13}=-\dfrac{29}{39}\)

\(\dfrac{5}{9}.\dfrac{-7}{13}+\dfrac{5}{9}.\dfrac{-9}{13}+\dfrac{5}{9}-\dfrac{3}{13}\)

= \(\dfrac{5}{9}.\left(\dfrac{-7}{13}+\dfrac{-9}{13}-\dfrac{3}{13}\right)\)

\(=\dfrac{5}{9}.\dfrac{-19}{13}\)

\(=\dfrac{-95}{117}\)

\(\dfrac{5}{9}\cdot\dfrac{7}{13}+\dfrac{5}{9}\cdot13-\dfrac{5}{9}\cdot\dfrac{3}{13}\)

\(=\dfrac{5}{9}\cdot\left(\dfrac{7}{13}-\dfrac{3}{13}+13\right)\)

\(=\dfrac{5}{9}\cdot\left(\dfrac{4}{13}+13\right)\)

\(=\dfrac{5}{9}\cdot\dfrac{173}{13}\)

\(=\dfrac{865}{117}\)

=5/9(7/13+13-3/13)

=5/9*(13+4/13)

=5/9*173/13=865/117

1: =-2/9(15/17+2/17)=-2/9

2: \(=\dfrac{-6}{3}+\dfrac{-21}{90}\)

=-2-7/30=-67/30

3: \(=\dfrac{3}{4}\cdot\dfrac{7}{5}+\dfrac{9}{7}\cdot\dfrac{3}{2}\)

=21/20+27/14=417/140

4: =-25/13(5/19+14/19)=-25/13

5: =-7/5-45/21=-7/5-15/7=-124/35

1: =-2/9(15/17+2/17)=-2/9

2: =34⋅75+97⋅32=34⋅75+97⋅32

=21/20+27/14=417/140

4: =-25/13(5/19+14/19)=-25/13

5: =-7/5-45/21=-7/5-15/7=-124/35

tính theo công thức bạn nhé