Bài 1:

a: \(=\dfrac{21}{7}\cdot\dfrac{15}{45}\cdot\dfrac{9}{18}=3\cdot\dfrac{1}{3}\cdot\dfrac{1}{2}=\dfrac{1}{2}\)

b: \(=\dfrac{11}{33}\cdot\dfrac{24}{8\cdot12}\cdot\dfrac{27}{9}=\dfrac{24}{96}=\dfrac{1}{4}\)

4 : 9 = \(\dfrac{4}{9}\)                         8 : 11 =\(\dfrac{8}{11}\)             7 : 15 =\(\dfrac{7}{15}\)

15 : 5 =  \(\dfrac{15}{5}=\dfrac{3}{1}\)                     63 : 21 =\(\dfrac{63}{21}\)           45 : 9 =\(\dfrac{45}{9}=\dfrac{5}{1}\)

6 : 18 =  \(\dfrac{6}{18}=\dfrac{1}{3}\)                       144 :  24 =\(\dfrac{244}{24}\)       7 =\(\dfrac{7}{1}\)

15 =  \(\dfrac{15}{1}\)                            10 = \(\dfrac{10}{1}\)                0 =\(\dfrac{0}{1}\)

\(4:9=\dfrac{4}{9};15:5=\dfrac{15}{5}=3;6:18=\dfrac{6}{18}=\dfrac{1}{3}\\ 15=\dfrac{15}{1};8:11=\dfrac{8}{11};63:21=\dfrac{63}{21}=3;144:24=\dfrac{144}{24};10=\dfrac{10}{1}\\ 7:15=\dfrac{7}{15};45:9=\dfrac{45}{9}=5;7=\dfrac{7}{1};0=0\)

hỏi cho vui thui mà Duy

14)

\(\left(27.45+27.55\right):\left(2+4+6+...+18\right)\)

\(=\left[27\left(45+55\right)\right]:\left[\frac{\left(18+2\right)9}{2}\right]\)

\(=\left(27.100\right):90\)

\(=2700:90\)

\(=30\)

15)

\(\left(26.180-26.12\right):\left(32-18+....+8-4\right)\) 

\(=26\left(180-12\right):\left(14+4+4+4+4+4+4+4\right)\)

\(=26.168:42\)

\(=84\)

a)=180:90

=2

b)=240:24

=10

c)=6480:540

=12

d)171:9

=19

a, 180 : (18.5) = 180 :90 = 2

b, 240 : (2.3.4) = 240 : 24 = 10

c, (15.18.24)  : ( 5.9.12)

 = 6480 : 540 =12

d, ( 27 + 45 + 18 + 81) : 9

 = 3 + 5 + 2 + 9 = 19

a, 180 : (18 .5) = 180 : 90 = 2

b,  240 : ( 2.3.4) = 240 : 24= 10

c, ( 15. 18. 24 ) : ( 5.9.12) =6480 : 540=12

d, ( 27 +45 + 18 +81) : 9

  =  171 : 9

  = 19

18 - 4\(x\) = -20 - 6\(x\) 

-4\(x\) + 6\(x\) = - 20  - 18

      2\(x\)    = - 38

         \(x\)  = - 19

h, -15 \(\times\) 24 = -7\(x\) + 32

     7\(x\) = 360 + 32

      7\(x\) = 392

         \(x\) =  392:7

          \(x\) = 56

i, 15\(x\) -3.(4\(x\) - 6) = -12 + 36

    15\(x\) - 12\(x\) + 18 =  24

      3\(x\) = 24 - 18

       3\(x\) = 6

         \(x\) = 2

k, -10\(x\) - 27 = -7\(x\) + 33

    -27 - 33 = -7\(x\) + 10\(x\)

     3\(x\) = -60

        \(x\) = -20

m, -17\(x\) - 24 = - 9\(x\) - 40

     - 24 + 40 =  -9\(x\) + 17\(x\)

          8\(x\) = 16

             \(x\) = 2

n, -23 \(\times\) 25 = -18\(x\) + 75

     -575 = -18\(x\) + 75

       18\(x\) = 575 + 75

        18\(x\) = 650

              \(x\) = \(\dfrac{325}{9}\)

Bài 1: 

a: =>x-7/18=-12/29:18/29=-3/2

=>x=-3/2+7/18=7/18-27/18=-20/18=-10/9

Bài 2: 

a: \(=\dfrac{1}{4}\cdot\dfrac{7}{3}\cdot30.05\cdot\dfrac{45}{8}=\dfrac{12621}{128}\)

Ta có:

14/15 = 168/180

47/45 = 188/180

5/4 = 225/180

14/15 = 168/180

47/45 = 188/180

5/4 = 225/180

7/12 = 42/72

11/18 = 44/72

25/24 = 75/72

\(\frac{48x700-24x45x20}{45-40+35-30+25-20+15-10}\)

\(=\frac{24x2x700-24x45x20}{5+5+5+5}\)

\(=\frac{24x1400-24x900}{20}\)

\(=\frac{24x\left(1400-900\right)}{20}\)

\(=\frac{24x500}{20}\)

\(=\frac{12000}{20}\)

\(=600\)

k nha

 

\(\frac{27x45+27x55}{2+4+6+...+16+18}\)

\(=\frac{27x\left(45+55\right)}{2+4+6+...+16+18}\)

\(=\frac{27x100}{2+4+6+...+16+18}\)

\(=\frac{2700}{\left(2+18\right)x9:2}\)

\(=\frac{2700}{90}\)

\(=30\)

k nha

 

\(\frac{26x108-26x12}{32-28+24-20+16-12+8-4}\)

\(=\frac{26x\left(108-12\right)}{4+4+4+4}\)

\(=\frac{26x96}{16}\)

\(=\frac{2496}{16}\)

\(=156\)

k nha