Giải:

a) -2/3.4/5+2/5:9/11

=-8/15+22/45

=-2/45

b) (-6,2:3,7):0,2

=-62/37:0,2

=-310/37

Chúc bạn học tốt!

a)-2/3.4/5+1/5:9/11

=-8/15+11/45

=-13/45

ok nhé!

1, \(\dfrac{-3}{5}:\dfrac{7}{5}-\dfrac{3}{5}:\dfrac{7}{5}+2\dfrac{3}{5}\)

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

\(=\dfrac{-6}{5}:\dfrac{7}{5}+\dfrac{13}{5}\)

\(=\dfrac{-6}{7}+\dfrac{13}{5}\\ =\dfrac{61}{35}\)

2, \(0,75-\left(2\dfrac{1}{3}+0,75\right)+3^2\cdot\left(-\dfrac{1}{9}\right)\)

\(=0,75-\dfrac{37}{12}+9\cdot\left(-\dfrac{1}{9}\right)\)

\(=-\dfrac{7}{3}+\left(-1\right)\\ -\dfrac{10}{3}\)

1/4 . -3/5 - 7/5 *1/4 +5/2 * 1/5

= -3/20- 7/20 + 10/20

= 0/20

chắc thế

\(\dfrac{-1}{9}.\dfrac{-3}{5}+\dfrac{5}{-6}.\dfrac{-3}{5}-\dfrac{7}{2}.\dfrac{3}{5}\)

\(=\dfrac{3}{5}.\left(\dfrac{1}{9}+\dfrac{5}{6}-\dfrac{7}{2}\right)\)

\(=\dfrac{3}{5}.\left(\dfrac{2}{18}+\dfrac{15}{18}-\dfrac{63}{18}\right)\)

\(=\dfrac{3}{5}.\left(-\dfrac{23}{9}\right)\)

\(=-\dfrac{69}{45}\)

a) \(A=\dfrac{2}{3}+\dfrac{3}{4}.\left(\dfrac{-4}{9}\right)=\dfrac{2}{3}-\dfrac{1}{3}=\dfrac{1}{3}\)

b) \(B=2\dfrac{3}{11}.1\dfrac{1}{12}.\left(-2,2\right)=\dfrac{25}{11}.\dfrac{13}{12}.\dfrac{-11}{5}=-\dfrac{65}{12}\)

c) \(C=\left(\dfrac{3}{4}-0,2\right)\left(0,4-\dfrac{4}{5}\right)=\left(\dfrac{3}{4}-\dfrac{1}{5}\right)\left(\dfrac{2}{5}-\dfrac{4}{5}\right)=\dfrac{11}{20}\left(\dfrac{-2}{5}\right)=\dfrac{-11}{50}\)

A = 2/3 + -1/3

    = 1/3

B = 25/11 . 13/12 . (-2,2)

    = 325/132 . (-2,2)

    = -65/12

C = 11/20 . -2/5

    = -11/50

Chúc bạn học tốt!! ^^

    = -

a, A = \(\dfrac{2}{3}+\dfrac{3}{4}.\left(\dfrac{-4}{9}\right)\)

       =\(\dfrac{2}{3}+\dfrac{-1}{3}\)

       =\(\dfrac{1}{3}\)

b, B = \(2\dfrac{3}{11}.1\dfrac{1}{12}.\left(-2,2\right)\)

       = \(\dfrac{23}{11}.\dfrac{13}{12}.\dfrac{-11}{5}\)

       = \(\dfrac{23.13.\left(-11\right)}{11.12.5}\)

       = \(\dfrac{-299}{60}\)

c, C =\(\left(\dfrac{3}{4}-0,2\right)\)\(.\left(0,4\right)-\dfrac{4}{5}\)

        = \(\left(\dfrac{3}{4}-\dfrac{1}{2}\right)\)\(.\dfrac{2}{5}-\dfrac{4}{5}\)

        = \(\left(\dfrac{3}{4}-\dfrac{2}{4}\right)\)\(.\dfrac{-2}{5}\)

        = \(\dfrac{1}{4}.\dfrac{-2}{5}\)

        = \(\dfrac{-2}{20}=\dfrac{-1}{10}\)

Chúc bạn học tốt!

a: \(=\dfrac{14-2+9}{32}\cdot\dfrac{4}{5}=\dfrac{21}{5}\cdot\dfrac{1}{8}=\dfrac{21}{40}\)

b: \(=10+\dfrac{2}{9}+2+\dfrac{3}{5}+6+\dfrac{2}{9}=18+\dfrac{47}{45}=\dfrac{857}{45}\)

c: \(=\dfrac{3}{10}-\dfrac{12}{5}+\dfrac{1}{10}=\dfrac{4}{10}-\dfrac{12}{5}=\dfrac{2}{5}-\dfrac{12}{5}=-2\)

d: \(=\dfrac{-25}{30}\left(\dfrac{37}{44}+\dfrac{13}{44}-\dfrac{6}{44}\right)=\dfrac{-25}{30}\cdot1=-\dfrac{5}{6}\)

A= 4/7.

Biết có cái

b) Quy luật: Từ số thứ 3 trở đi thì số sau bằng hai số trước cộng lại

=> Dãy số sẽ là: 1;2;3;5;8;13;21;34;55;89

c) Quy luật: Từ số thứ 5 trở đi thì số sau bằng tổng 4 số trước đó

=> Dãy số sẽ là 1;1;1;1;4;7;13;25;59;104

Bạn ơi phần a) đâu ạ?

phần a) mk giup bạn công thức tổng quát là (2n-1)/3n

`[-5]/13 . 2/11+[-5]/11 . 9/13+1`

`=[-5]/13 . 2/11+[-5]/13 . 9/11+1`

`=[-5]/13 . (2/11+9/11)+1`

`=[-5]/13 . 11/11+1`

`=[-5]/13+1=[-5]/13+13/13=8/13`

\(\dfrac{-5}{13}.\dfrac{2}{11}+\dfrac{-5}{13}.\dfrac{9}{13}+1\)

\(=\dfrac{-5}{13}+\left(\dfrac{2}{11}+\dfrac{9}{11}\right)+1\)

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

\(=\dfrac{-5}{13}+1\)

\(=\dfrac{8}{13}\)